1 ================================ 1 ================================
2 Documentation for /proc/sys/net/ 2 Documentation for /proc/sys/net/
3 ================================ 3 ================================
4 4
5 Copyright 5 Copyright
6 6
7 Copyright (c) 1999 7 Copyright (c) 1999
8 8
9 - Terrehon Bowden <terrehon@pacbell.net 9 - Terrehon Bowden <terrehon@pacbell.net>
10 - Bodo Bauer <bb@ricochet.net> 10 - Bodo Bauer <bb@ricochet.net>
11 11
12 Copyright (c) 2000 12 Copyright (c) 2000
13 13
14 - Jorge Nerin <comandante@zaralinux.com 14 - Jorge Nerin <comandante@zaralinux.com>
15 15
16 Copyright (c) 2009 16 Copyright (c) 2009
17 17
18 - Shen Feng <shen@cn.fujitsu.com> 18 - Shen Feng <shen@cn.fujitsu.com>
19 19
20 For general info and legal blurb, please look 20 For general info and legal blurb, please look in index.rst.
21 21
22 ---------------------------------------------- 22 ------------------------------------------------------------------------------
23 23
24 This file contains the documentation for the s 24 This file contains the documentation for the sysctl files in
25 /proc/sys/net 25 /proc/sys/net
26 26
27 The interface to the networking parts of 27 The interface to the networking parts of the kernel is located in
28 /proc/sys/net. The following table shows all p 28 /proc/sys/net. The following table shows all possible subdirectories. You may
29 see only some of them, depending on your kerne 29 see only some of them, depending on your kernel's configuration.
30 30
31 31
32 Table : Subdirectories in /proc/sys/net 32 Table : Subdirectories in /proc/sys/net
33 33
34 ========= =================== = ========== == 34 ========= =================== = ========== ===================
35 Directory Content Directory Co 35 Directory Content Directory Content
36 ========= =================== = ========== == 36 ========= =================== = ========== ===================
37 802 E802 protocol mptcp Mu 37 802 E802 protocol mptcp Multipath TCP
38 appletalk Appletalk protocol netfilter Ne 38 appletalk Appletalk protocol netfilter Network Filter
39 ax25 AX25 netrom NE 39 ax25 AX25 netrom NET/ROM
40 bridge Bridging rose X. 40 bridge Bridging rose X.25 PLP layer
41 core General parameter tipc TI 41 core General parameter tipc TIPC
42 ethernet Ethernet protocol unix Un 42 ethernet Ethernet protocol unix Unix domain sockets
43 ipv4 IP version 4 x25 X. 43 ipv4 IP version 4 x25 X.25 protocol
44 ipv6 IP version 6 44 ipv6 IP version 6
45 ========= =================== = ========== == 45 ========= =================== = ========== ===================
46 46
47 1. /proc/sys/net/core - Network core options 47 1. /proc/sys/net/core - Network core options
48 ============================================ 48 ============================================
49 49
50 bpf_jit_enable 50 bpf_jit_enable
51 -------------- 51 --------------
52 52
53 This enables the BPF Just in Time (JIT) compil 53 This enables the BPF Just in Time (JIT) compiler. BPF is a flexible
54 and efficient infrastructure allowing to execu 54 and efficient infrastructure allowing to execute bytecode at various
55 hook points. It is used in a number of Linux k 55 hook points. It is used in a number of Linux kernel subsystems such
56 as networking (e.g. XDP, tc), tracing (e.g. kp 56 as networking (e.g. XDP, tc), tracing (e.g. kprobes, uprobes, tracepoints)
57 and security (e.g. seccomp). LLVM has a BPF ba 57 and security (e.g. seccomp). LLVM has a BPF back end that can compile
58 restricted C into a sequence of BPF instructio 58 restricted C into a sequence of BPF instructions. After program load
59 through bpf(2) and passing a verifier in the k 59 through bpf(2) and passing a verifier in the kernel, a JIT will then
60 translate these BPF proglets into native CPU i 60 translate these BPF proglets into native CPU instructions. There are
61 two flavors of JITs, the newer eBPF JIT curren 61 two flavors of JITs, the newer eBPF JIT currently supported on:
62 62
63 - x86_64 63 - x86_64
64 - x86_32 64 - x86_32
65 - arm64 65 - arm64
66 - arm32 66 - arm32
67 - ppc64 67 - ppc64
68 - ppc32 <<
69 - sparc64 68 - sparc64
70 - mips64 69 - mips64
71 - s390x 70 - s390x
72 - riscv64 71 - riscv64
73 - riscv32 72 - riscv32
74 - loongarch64 <<
75 - arc <<
76 73
77 And the older cBPF JIT supported on the follow 74 And the older cBPF JIT supported on the following archs:
78 75
79 - mips 76 - mips
>> 77 - ppc
80 - sparc 78 - sparc
81 79
82 eBPF JITs are a superset of cBPF JITs, meaning 80 eBPF JITs are a superset of cBPF JITs, meaning the kernel will
83 migrate cBPF instructions into eBPF instructio 81 migrate cBPF instructions into eBPF instructions and then JIT
84 compile them transparently. Older cBPF JITs ca 82 compile them transparently. Older cBPF JITs can only translate
85 tcpdump filters, seccomp rules, etc, but not m 83 tcpdump filters, seccomp rules, etc, but not mentioned eBPF
86 programs loaded through bpf(2). 84 programs loaded through bpf(2).
87 85
88 Values: 86 Values:
89 87
90 - 0 - disable the JIT (default value) 88 - 0 - disable the JIT (default value)
91 - 1 - enable the JIT 89 - 1 - enable the JIT
92 - 2 - enable the JIT and ask the compi 90 - 2 - enable the JIT and ask the compiler to emit traces on kernel log.
93 91
94 bpf_jit_harden 92 bpf_jit_harden
95 -------------- 93 --------------
96 94
97 This enables hardening for the BPF JIT compile 95 This enables hardening for the BPF JIT compiler. Supported are eBPF
98 JIT backends. Enabling hardening trades off pe 96 JIT backends. Enabling hardening trades off performance, but can
99 mitigate JIT spraying. 97 mitigate JIT spraying.
100 98
101 Values: 99 Values:
102 100
103 - 0 - disable JIT hardening (default v 101 - 0 - disable JIT hardening (default value)
104 - 1 - enable JIT hardening for unprivi 102 - 1 - enable JIT hardening for unprivileged users only
105 - 2 - enable JIT hardening for all use 103 - 2 - enable JIT hardening for all users
106 104
107 where "privileged user" in this context means <<
108 CAP_BPF or CAP_SYS_ADMIN in the root user name <<
109 <<
110 bpf_jit_kallsyms 105 bpf_jit_kallsyms
111 ---------------- 106 ----------------
112 107
113 When BPF JIT compiler is enabled, then compile 108 When BPF JIT compiler is enabled, then compiled images are unknown
114 addresses to the kernel, meaning they neither 109 addresses to the kernel, meaning they neither show up in traces nor
115 in /proc/kallsyms. This enables export of thes 110 in /proc/kallsyms. This enables export of these addresses, which can
116 be used for debugging/tracing. If bpf_jit_hard 111 be used for debugging/tracing. If bpf_jit_harden is enabled, this
117 feature is disabled. 112 feature is disabled.
118 113
119 Values : 114 Values :
120 115
121 - 0 - disable JIT kallsyms export (def 116 - 0 - disable JIT kallsyms export (default value)
122 - 1 - enable JIT kallsyms export for p 117 - 1 - enable JIT kallsyms export for privileged users only
123 118
124 bpf_jit_limit 119 bpf_jit_limit
125 ------------- 120 -------------
126 121
127 This enforces a global limit for memory alloca 122 This enforces a global limit for memory allocations to the BPF JIT
128 compiler in order to reject unprivileged JIT r 123 compiler in order to reject unprivileged JIT requests once it has
129 been surpassed. bpf_jit_limit contains the val 124 been surpassed. bpf_jit_limit contains the value of the global limit
130 in bytes. 125 in bytes.
131 126
132 dev_weight 127 dev_weight
133 ---------- 128 ----------
134 129
135 The maximum number of packets that kernel can 130 The maximum number of packets that kernel can handle on a NAPI interrupt,
136 it's a Per-CPU variable. For drivers that supp 131 it's a Per-CPU variable. For drivers that support LRO or GRO_HW, a hardware
137 aggregated packet is counted as one packet in 132 aggregated packet is counted as one packet in this context.
138 133
139 Default: 64 134 Default: 64
140 135
141 dev_weight_rx_bias 136 dev_weight_rx_bias
142 ------------------ 137 ------------------
143 138
144 RPS (e.g. RFS, aRFS) processing is competing w 139 RPS (e.g. RFS, aRFS) processing is competing with the registered NAPI poll function
145 of the driver for the per softirq cycle netdev 140 of the driver for the per softirq cycle netdev_budget. This parameter influences
146 the proportion of the configured netdev_budget 141 the proportion of the configured netdev_budget that is spent on RPS based packet
147 processing during RX softirq cycles. It is fur 142 processing during RX softirq cycles. It is further meant for making current
148 dev_weight adaptable for asymmetric CPU needs 143 dev_weight adaptable for asymmetric CPU needs on RX/TX side of the network stack.
149 (see dev_weight_tx_bias) It is effective on a 144 (see dev_weight_tx_bias) It is effective on a per CPU basis. Determination is based
150 on dev_weight and is calculated multiplicative 145 on dev_weight and is calculated multiplicative (dev_weight * dev_weight_rx_bias).
151 146
152 Default: 1 147 Default: 1
153 148
154 dev_weight_tx_bias 149 dev_weight_tx_bias
155 ------------------ 150 ------------------
156 151
157 Scales the maximum number of packets that can 152 Scales the maximum number of packets that can be processed during a TX softirq cycle.
158 Effective on a per CPU basis. Allows scaling o 153 Effective on a per CPU basis. Allows scaling of current dev_weight for asymmetric
159 net stack processing needs. Be careful to avoi 154 net stack processing needs. Be careful to avoid making TX softirq processing a CPU hog.
160 155
161 Calculation is based on dev_weight (dev_weight 156 Calculation is based on dev_weight (dev_weight * dev_weight_tx_bias).
162 157
163 Default: 1 158 Default: 1
164 159
165 default_qdisc 160 default_qdisc
166 ------------- 161 -------------
167 162
168 The default queuing discipline to use for netw 163 The default queuing discipline to use for network devices. This allows
169 overriding the default of pfifo_fast with an a 164 overriding the default of pfifo_fast with an alternative. Since the default
170 queuing discipline is created without addition 165 queuing discipline is created without additional parameters so is best suited
171 to queuing disciplines that work well without 166 to queuing disciplines that work well without configuration like stochastic
172 fair queue (sfq), CoDel (codel) or fair queue 167 fair queue (sfq), CoDel (codel) or fair queue CoDel (fq_codel). Don't use
173 queuing disciplines like Hierarchical Token Bu 168 queuing disciplines like Hierarchical Token Bucket or Deficit Round Robin
174 which require setting up classes and bandwidth 169 which require setting up classes and bandwidths. Note that physical multiqueue
175 interfaces still use mq as root qdisc, which i 170 interfaces still use mq as root qdisc, which in turn uses this default for its
176 leaves. Virtual devices (like e.g. lo or veth) 171 leaves. Virtual devices (like e.g. lo or veth) ignore this setting and instead
177 default to noqueue. 172 default to noqueue.
178 173
179 Default: pfifo_fast 174 Default: pfifo_fast
180 175
181 busy_read 176 busy_read
182 --------- 177 ---------
183 178
184 Low latency busy poll timeout for socket reads 179 Low latency busy poll timeout for socket reads. (needs CONFIG_NET_RX_BUSY_POLL)
185 Approximate time in us to busy loop waiting fo 180 Approximate time in us to busy loop waiting for packets on the device queue.
186 This sets the default value of the SO_BUSY_POL 181 This sets the default value of the SO_BUSY_POLL socket option.
187 Can be set or overridden per socket by setting 182 Can be set or overridden per socket by setting socket option SO_BUSY_POLL,
188 which is the preferred method of enabling. If 183 which is the preferred method of enabling. If you need to enable the feature
189 globally via sysctl, a value of 50 is recommen 184 globally via sysctl, a value of 50 is recommended.
190 185
191 Will increase power usage. 186 Will increase power usage.
192 187
193 Default: 0 (off) 188 Default: 0 (off)
194 189
195 busy_poll 190 busy_poll
196 ---------------- 191 ----------------
197 Low latency busy poll timeout for poll and sel 192 Low latency busy poll timeout for poll and select. (needs CONFIG_NET_RX_BUSY_POLL)
198 Approximate time in us to busy loop waiting fo 193 Approximate time in us to busy loop waiting for events.
199 Recommended value depends on the number of soc 194 Recommended value depends on the number of sockets you poll on.
200 For several sockets 50, for several hundreds 1 195 For several sockets 50, for several hundreds 100.
201 For more than that you probably want to use ep 196 For more than that you probably want to use epoll.
202 Note that only sockets with SO_BUSY_POLL set w 197 Note that only sockets with SO_BUSY_POLL set will be busy polled,
203 so you want to either selectively set SO_BUSY_ 198 so you want to either selectively set SO_BUSY_POLL on those sockets or set
204 sysctl.net.busy_read globally. 199 sysctl.net.busy_read globally.
205 200
206 Will increase power usage. 201 Will increase power usage.
207 202
208 Default: 0 (off) 203 Default: 0 (off)
209 204
210 mem_pcpu_rsv <<
211 ------------ <<
212 <<
213 Per-cpu reserved forward alloc cache size in p <<
214 <<
215 rmem_default 205 rmem_default
216 ------------ 206 ------------
217 207
218 The default setting of the socket receive buff 208 The default setting of the socket receive buffer in bytes.
219 209
220 rmem_max 210 rmem_max
221 -------- 211 --------
222 212
223 The maximum receive socket buffer size in byte 213 The maximum receive socket buffer size in bytes.
224 214
225 rps_default_mask <<
226 ---------------- <<
227 <<
228 The default RPS CPU mask used on newly created <<
229 mask means RPS disabled by default. <<
230 <<
231 tstamp_allow_data 215 tstamp_allow_data
232 ----------------- 216 -----------------
233 Allow processes to receive tx timestamps loope 217 Allow processes to receive tx timestamps looped together with the original
234 packet contents. If disabled, transmit timesta 218 packet contents. If disabled, transmit timestamp requests from unprivileged
235 processes are dropped unless socket option SOF 219 processes are dropped unless socket option SOF_TIMESTAMPING_OPT_TSONLY is set.
236 220
237 Default: 1 (on) 221 Default: 1 (on)
238 222
239 223
240 wmem_default 224 wmem_default
241 ------------ 225 ------------
242 226
243 The default setting (in bytes) of the socket s 227 The default setting (in bytes) of the socket send buffer.
244 228
245 wmem_max 229 wmem_max
246 -------- 230 --------
247 231
248 The maximum send socket buffer size in bytes. 232 The maximum send socket buffer size in bytes.
249 233
250 message_burst and message_cost 234 message_burst and message_cost
251 ------------------------------ 235 ------------------------------
252 236
253 These parameters are used to limit the warnin 237 These parameters are used to limit the warning messages written to the kernel
254 log from the networking code. They enforc 238 log from the networking code. They enforce a rate limit to make a
255 denial-of-service attack impossible. A higher 239 denial-of-service attack impossible. A higher message_cost factor, results in
256 fewer messages that will be written. Message_b 240 fewer messages that will be written. Message_burst controls when messages will
257 be dropped. The default settings limit wa 241 be dropped. The default settings limit warning messages to one every five
258 seconds. 242 seconds.
259 243
260 warnings 244 warnings
261 -------- 245 --------
262 246
263 This sysctl is now unused. 247 This sysctl is now unused.
264 248
265 This was used to control console messages from 249 This was used to control console messages from the networking stack that
266 occur because of problems on the network like 250 occur because of problems on the network like duplicate address or bad
267 checksums. 251 checksums.
268 252
269 These messages are now emitted at KERN_DEBUG a 253 These messages are now emitted at KERN_DEBUG and can generally be enabled
270 and controlled by the dynamic_debug facility. 254 and controlled by the dynamic_debug facility.
271 255
272 netdev_budget 256 netdev_budget
273 ------------- 257 -------------
274 258
275 Maximum number of packets taken from all inter 259 Maximum number of packets taken from all interfaces in one polling cycle (NAPI
276 poll). In one polling cycle interfaces which a 260 poll). In one polling cycle interfaces which are registered to polling are
277 probed in a round-robin manner. Also, a pollin 261 probed in a round-robin manner. Also, a polling cycle may not exceed
278 netdev_budget_usecs microseconds, even if netd 262 netdev_budget_usecs microseconds, even if netdev_budget has not been
279 exhausted. 263 exhausted.
280 264
281 netdev_budget_usecs 265 netdev_budget_usecs
282 --------------------- 266 ---------------------
283 267
284 Maximum number of microseconds in one NAPI pol 268 Maximum number of microseconds in one NAPI polling cycle. Polling
285 will exit when either netdev_budget_usecs have 269 will exit when either netdev_budget_usecs have elapsed during the
286 poll cycle or the number of packets processed 270 poll cycle or the number of packets processed reaches netdev_budget.
287 271
288 netdev_max_backlog 272 netdev_max_backlog
289 ------------------ 273 ------------------
290 274
291 Maximum number of packets, queued on the INPUT 275 Maximum number of packets, queued on the INPUT side, when the interface
292 receives packets faster than kernel can proces 276 receives packets faster than kernel can process them.
293 277
294 netdev_rss_key 278 netdev_rss_key
295 -------------- 279 --------------
296 280
297 RSS (Receive Side Scaling) enabled drivers use 281 RSS (Receive Side Scaling) enabled drivers use a 40 bytes host key that is
298 randomly generated. 282 randomly generated.
299 Some user space might need to gather its conte 283 Some user space might need to gather its content even if drivers do not
300 provide ethtool -x support yet. 284 provide ethtool -x support yet.
301 285
302 :: 286 ::
303 287
304 myhost:~# cat /proc/sys/net/core/netdev_rss_ 288 myhost:~# cat /proc/sys/net/core/netdev_rss_key
305 84:50:f4:00:a8:15:d1:a7:e9:7f:1d:60:35:c7:47 289 84:50:f4:00:a8:15:d1:a7:e9:7f:1d:60:35:c7:47:25:42:97:74:ca:56:bb:b6:a1:d8: ... (52 bytes total)
306 290
307 File contains nul bytes if no driver ever call 291 File contains nul bytes if no driver ever called netdev_rss_key_fill() function.
308 292
309 Note: 293 Note:
310 /proc/sys/net/core/netdev_rss_key contains 5 294 /proc/sys/net/core/netdev_rss_key contains 52 bytes of key,
311 but most drivers only use 40 bytes of it. 295 but most drivers only use 40 bytes of it.
312 296
313 :: 297 ::
314 298
315 myhost:~# ethtool -x eth0 299 myhost:~# ethtool -x eth0
316 RX flow hash indirection table for eth0 with 300 RX flow hash indirection table for eth0 with 8 RX ring(s):
317 0: 0 1 2 3 4 5 301 0: 0 1 2 3 4 5 6 7
318 RSS hash key: 302 RSS hash key:
319 84:50:f4:00:a8:15:d1:a7:e9:7f:1d:60:35:c7:47 303 84:50:f4:00:a8:15:d1:a7:e9:7f:1d:60:35:c7:47:25:42:97:74:ca:56:bb:b6:a1:d8:43:e3:c9:0c:fd:17:55:c2:3a:4d:69:ed:f1:42:89
320 304
321 netdev_tstamp_prequeue 305 netdev_tstamp_prequeue
322 ---------------------- 306 ----------------------
323 307
324 If set to 0, RX packet timestamps can be sampl 308 If set to 0, RX packet timestamps can be sampled after RPS processing, when
325 the target CPU processes packets. It might giv 309 the target CPU processes packets. It might give some delay on timestamps, but
326 permit to distribute the load on several cpus. 310 permit to distribute the load on several cpus.
327 311
328 If set to 1 (default), timestamps are sampled 312 If set to 1 (default), timestamps are sampled as soon as possible, before
329 queueing. 313 queueing.
330 314
331 netdev_unregister_timeout_secs <<
332 ------------------------------ <<
333 <<
334 Unregister network device timeout in seconds. <<
335 This option controls the timeout (in seconds) <<
336 waiting for a network device refcount to drop <<
337 unregistration. A lower value may be useful du <<
338 a leaked reference faster. A larger value may <<
339 warnings on slow/loaded systems. <<
340 Default value is 10, minimum 1, maximum 3600. <<
341 <<
342 skb_defer_max <<
343 ------------- <<
344 <<
345 Max size (in skbs) of the per-cpu list of skbs <<
346 by the cpu which allocated them. Used by TCP s <<
347 <<
348 Default: 64 <<
349 <<
350 optmem_max 315 optmem_max
351 ---------- 316 ----------
352 317
353 Maximum ancillary buffer size allowed per sock 318 Maximum ancillary buffer size allowed per socket. Ancillary data is a sequence
354 of struct cmsghdr structures with appended dat !! 319 of struct cmsghdr structures with appended data.
355 optmem_max as a limit for its internal structu <<
356 <<
357 Default : 128 KB <<
358 320
359 fb_tunnels_only_for_init_net 321 fb_tunnels_only_for_init_net
360 ---------------------------- 322 ----------------------------
361 323
362 Controls if fallback tunnels (like tunl0, gre0 324 Controls if fallback tunnels (like tunl0, gre0, gretap0, erspan0,
363 sit0, ip6tnl0, ip6gre0) are automatically crea 325 sit0, ip6tnl0, ip6gre0) are automatically created. There are 3 possibilities
364 (a) value = 0; respective fallback tunnels are 326 (a) value = 0; respective fallback tunnels are created when module is
365 loaded in every net namespaces (backward compa 327 loaded in every net namespaces (backward compatible behavior).
366 (b) value = 1; [kcmd value: initns] respective 328 (b) value = 1; [kcmd value: initns] respective fallback tunnels are
367 created only in init net namespace and every o 329 created only in init net namespace and every other net namespace will
368 not have them. 330 not have them.
369 (c) value = 2; [kcmd value: none] fallback tun 331 (c) value = 2; [kcmd value: none] fallback tunnels are not created
370 when a module is loaded in any of the net name 332 when a module is loaded in any of the net namespace. Setting value to
371 "2" is pointless after boot if these modules a 333 "2" is pointless after boot if these modules are built-in, so there is
372 a kernel command-line option that can change t 334 a kernel command-line option that can change this default. Please refer to
373 Documentation/admin-guide/kernel-parameters.tx 335 Documentation/admin-guide/kernel-parameters.txt for additional details.
374 336
375 Not creating fallback tunnels gives control to 337 Not creating fallback tunnels gives control to userspace to create
376 whatever is needed only and avoid creating dev 338 whatever is needed only and avoid creating devices which are redundant.
377 339
378 Default : 0 (for compatibility reasons) 340 Default : 0 (for compatibility reasons)
379 341
380 devconf_inherit_init_net 342 devconf_inherit_init_net
381 ------------------------ 343 ------------------------
382 344
383 Controls if a new network namespace should inh 345 Controls if a new network namespace should inherit all current
384 settings under /proc/sys/net/{ipv4,ipv6}/conf/ 346 settings under /proc/sys/net/{ipv4,ipv6}/conf/{all,default}/. By
385 default, we keep the current behavior: for IPv 347 default, we keep the current behavior: for IPv4 we inherit all current
386 settings from init_net and for IPv6 we reset a 348 settings from init_net and for IPv6 we reset all settings to default.
387 349
388 If set to 1, both IPv4 and IPv6 settings are f 350 If set to 1, both IPv4 and IPv6 settings are forced to inherit from
389 current ones in init_net. If set to 2, both IP 351 current ones in init_net. If set to 2, both IPv4 and IPv6 settings are
390 forced to reset to their default values. If se 352 forced to reset to their default values. If set to 3, both IPv4 and IPv6
391 settings are forced to inherit from current on 353 settings are forced to inherit from current ones in the netns where this
392 new netns has been created. 354 new netns has been created.
393 355
394 Default : 0 (for compatibility reasons) 356 Default : 0 (for compatibility reasons)
395 <<
396 txrehash <<
397 -------- <<
398 <<
399 Controls default hash rethink behaviour on soc <<
400 to SOCK_TXREHASH_DEFAULT (i. e. not overridden <<
401 <<
402 If set to 1 (default), hash rethink is perform <<
403 If set to 0, hash rethink is not performed. <<
404 <<
405 gro_normal_batch <<
406 ---------------- <<
407 <<
408 Maximum number of the segments to batch up on <<
409 exits GRO, either as a coalesced superframe or <<
410 GRO has decided not to coalesce, it is placed <<
411 list is then passed to the stack when the numb <<
412 gro_normal_batch limit. <<
413 <<
414 high_order_alloc_disable <<
415 ------------------------ <<
416 <<
417 By default the allocator for page frags tries <<
418 on x86). While the default behavior gives good <<
419 might have hit a contention in page allocation <<
420 true on older kernels (< 5.14) when high-order <<
421 lists. This allows to opt-in for order-0 alloc <<
422 historical importance. <<
423 <<
424 Default: 0 <<
425 357
426 2. /proc/sys/net/unix - Parameters for Unix do 358 2. /proc/sys/net/unix - Parameters for Unix domain sockets
427 ---------------------------------------------- 359 ----------------------------------------------------------
428 360
429 There is only one file in this directory. 361 There is only one file in this directory.
430 unix_dgram_qlen limits the max number of datag 362 unix_dgram_qlen limits the max number of datagrams queued in Unix domain
431 socket's buffer. It will not take effect unles 363 socket's buffer. It will not take effect unless PF_UNIX flag is specified.
432 364
433 365
434 3. /proc/sys/net/ipv4 - IPV4 settings 366 3. /proc/sys/net/ipv4 - IPV4 settings
435 ------------------------------------- 367 -------------------------------------
436 Please see: Documentation/networking/ip-sysctl 368 Please see: Documentation/networking/ip-sysctl.rst and
437 Documentation/admin-guide/sysctl/net.rst for d 369 Documentation/admin-guide/sysctl/net.rst for descriptions of these entries.
438 370
439 371
440 4. Appletalk 372 4. Appletalk
441 ------------ 373 ------------
442 374
443 The /proc/sys/net/appletalk directory holds 375 The /proc/sys/net/appletalk directory holds the Appletalk configuration data
444 when Appletalk is loaded. The configurable par 376 when Appletalk is loaded. The configurable parameters are:
445 377
446 aarp-expiry-time 378 aarp-expiry-time
447 ---------------- 379 ----------------
448 380
449 The amount of time we keep an ARP entry bef 381 The amount of time we keep an ARP entry before expiring it. Used to age out
450 old hosts. 382 old hosts.
451 383
452 aarp-resolve-time 384 aarp-resolve-time
453 ----------------- 385 -----------------
454 386
455 The amount of time we will spend trying to res 387 The amount of time we will spend trying to resolve an Appletalk address.
456 388
457 aarp-retransmit-limit 389 aarp-retransmit-limit
458 --------------------- 390 ---------------------
459 391
460 The number of times we will retransmit a query 392 The number of times we will retransmit a query before giving up.
461 393
462 aarp-tick-time 394 aarp-tick-time
463 -------------- 395 --------------
464 396
465 Controls the rate at which expires are checked 397 Controls the rate at which expires are checked.
466 398
467 The directory /proc/net/appletalk holds the 399 The directory /proc/net/appletalk holds the list of active Appletalk sockets
468 on a machine. 400 on a machine.
469 401
470 The fields indicate the DDP type, the local 402 The fields indicate the DDP type, the local address (in network:node format)
471 the remote address, the size of the transmi 403 the remote address, the size of the transmit pending queue, the size of the
472 received queue (bytes waiting for application 404 received queue (bytes waiting for applications to read) the state and the uid
473 owning the socket. 405 owning the socket.
474 406
475 /proc/net/atalk_iface lists all the interfa 407 /proc/net/atalk_iface lists all the interfaces configured for appletalk.It
476 shows the name of the interface, its Appleta 408 shows the name of the interface, its Appletalk address, the network range on
477 that address (or network number for phase 1 409 that address (or network number for phase 1 networks), and the status of the
478 interface. 410 interface.
479 411
480 /proc/net/atalk_route lists each known netw 412 /proc/net/atalk_route lists each known network route. It lists the target
481 (network) that the route leads to, the router 413 (network) that the route leads to, the router (may be directly connected), the
482 route flags, and the device the route is using 414 route flags, and the device the route is using.
483 415
484 5. TIPC 416 5. TIPC
485 ------- 417 -------
486 418
487 tipc_rmem 419 tipc_rmem
488 --------- 420 ---------
489 421
490 The TIPC protocol now has a tunable for the re 422 The TIPC protocol now has a tunable for the receive memory, similar to the
491 tcp_rmem - i.e. a vector of 3 INTEGERs: (min, 423 tcp_rmem - i.e. a vector of 3 INTEGERs: (min, default, max)
492 424
493 :: 425 ::
494 426
495 # cat /proc/sys/net/tipc/tipc_rmem 427 # cat /proc/sys/net/tipc/tipc_rmem
496 4252725 34021800 68043600 428 4252725 34021800 68043600
497 # 429 #
498 430
499 The max value is set to CONN_OVERLOAD_LIMIT, a 431 The max value is set to CONN_OVERLOAD_LIMIT, and the default and min values
500 are scaled (shifted) versions of that same val 432 are scaled (shifted) versions of that same value. Note that the min value
501 is not at this point in time used in any meani 433 is not at this point in time used in any meaningful way, but the triplet is
502 preserved in order to be consistent with thing 434 preserved in order to be consistent with things like tcp_rmem.
503 435
504 named_timeout 436 named_timeout
505 ------------- 437 -------------
506 438
507 TIPC name table updates are distributed asynch 439 TIPC name table updates are distributed asynchronously in a cluster, without
508 any form of transaction handling. This means t 440 any form of transaction handling. This means that different race scenarios are
509 possible. One such is that a name withdrawal s 441 possible. One such is that a name withdrawal sent out by one node and received
510 by another node may arrive after a second, ove 442 by another node may arrive after a second, overlapping name publication already
511 has been accepted from a third node, although 443 has been accepted from a third node, although the conflicting updates
512 originally may have been issued in the correct 444 originally may have been issued in the correct sequential order.
513 If named_timeout is nonzero, failed topology u 445 If named_timeout is nonzero, failed topology updates will be placed on a defer
514 queue until another event arrives that clears 446 queue until another event arrives that clears the error, or until the timeout
515 expires. Value is in milliseconds. 447 expires. Value is in milliseconds.
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