kernel/include/net/snmp.h, branch linux-3.17.y

net: clean up snmp stats code

2014-05-07T20:06:05Z

commit 8f0ea0fe3a036a47767f9c80e (snmp: reduce percpu needs by 50%) reduced snmp array size to 1, so technically it doesn't have to be an array any more. What's more, after the following commit: commit 933393f58fef9963eac61db8093689544e29a600 Date: Thu Dec 22 11:58:51 2011 -0600 percpu: Remove irqsafe_cpu_xxx variants We simply say that regular this_cpu use must be safe regardless of preemption and interrupt state. That has no material change for x86 and s390 implementations of this_cpu operations. However, arches that do not provide their own implementation for this_cpu operations will now get code generated that disables interrupts instead of preemption. probably no arch wants to have SNMP_ARRAY_SZ == 2. At least after almost 3 years, no one complains. So, just convert the array to a single pointer and remove snmp_mib_init() and snmp_mib_free() as well. Cc: Christoph Lameter Cc: Eric Dumazet Cc: David S. Miller Signed-off-by: Cong Wang Signed-off-by: David S. Miller

net: avoid reloads in SNMP_UPD_PO_STATS

2012-08-06T20:40:47Z

Avoid two instructions to reload dev->nd_net->mib.ip_statistics pointer, unsing a temp variable, in ip_rcv(), ip_output() paths for example. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

Merge branch 'for-3.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu

2012-01-09T21:08:28Z

* 'for-3.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: percpu: Remove irqsafe_cpu_xxx variants Fix up conflict in arch/x86/include/asm/percpu.h due to clash with cebef5beed3d ("x86: Fix and improve percpu_cmpxchg{8,16}b_double()") which edited the (now removed) irqsafe_cpu_cmpxchg*_double code.

percpu: Remove irqsafe_cpu_xxx variants

2011-12-22T18:40:20Z

We simply say that regular this_cpu use must be safe regardless of preemption and interrupt state. That has no material change for x86 and s390 implementations of this_cpu operations. However, arches that do not provide their own implementation for this_cpu operations will now get code generated that disables interrupts instead of preemption. -tj: This is part of on-going percpu API cleanup. For detailed discussion of the subject, please refer to the following thread. http://thread.gmane.org/gmane.linux.kernel/1222078 Signed-off-by: Christoph Lameter Signed-off-by: Tejun Heo LKML-Reference:

ipv6: reduce percpu needs for icmpv6msg mibs

2011-11-14T05:12:26Z

Reading /proc/net/snmp6 on a machine with a lot of cpus is very expensive (can be ~88000 us). This is because ICMPV6MSG MIB uses 4096 bytes per cpu, and folding values for all possible cpus can read 16 Mbytes of memory (32MBytes on non x86 arches) ICMP messages are not considered as fast path on a typical server, and eventually few cpus handle them anyway. We can afford an atomic operation instead of using percpu data. This saves 4096 bytes per cpu and per network namespace. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

ipv4: reduce percpu needs for icmpmsg mibs

2011-11-09T21:04:20Z

Reading /proc/net/snmp on a machine with a lot of cpus is very expensive (can be ~88000 us). This is because ICMPMSG MIB uses 4096 bytes per cpu, and folding values for all possible cpus can read 16 Mbytes of memory. ICMP messages are not considered as fast path on a typical server, and eventually few cpus handle them anyway. We can afford an atomic operation instead of using percpu data. This saves 4096 bytes per cpu and per network namespace. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

snmp: reduce percpu needs by 50%

2011-06-11T23:23:59Z

SNMP mibs use two percpu arrays, one used in BH context, another in USER context. With increasing number of cpus in machines, and fact that ipv6 uses per network device ipstats_mib, this is consuming a lot of memory if many network devices are registered. commit be281e554e2a (ipv6: reduce per device ICMP mib sizes) shrinked percpu needs for ipv6, but we can reduce memory use a bit more. With recent percpu infrastructure (irqsafe_cpu_inc() ...), we no longer need this BH/USER separation since we can update counters in a single x86 instruction, regardless of the BH/USER context. Other arches than x86 might need to disable irq in their irqsafe_cpu_inc() implementation : If this happens to be a problem, we can make SNMP_ARRAY_SZ arch dependent, but a previous poll ( https://lkml.org/lkml/2011/3/17/174 ) to arch maintainers did not raise strong opposition. Only on 32bit arches, we need to disable BH for 64bit counters updates done from USER context (currently used for IP MIB) This also reduces vmlinux size : 1) x86_64 build $ size vmlinux.before vmlinux.after text data bss dec hex filename 7853650 1293772 1896448 11043870 a8841e vmlinux.before 7850578 1293772 1896448 11040798 a8781e vmlinux.after 2) i386 build $ size vmlinux.before vmlinux.afterpatch text data bss dec hex filename 6039335 635076 3670016 10344427 9dd7eb vmlinux.before 6037342 635076 3670016 10342434 9dd022 vmlinux.afterpatch Signed-off-by: Eric Dumazet CC: Andi Kleen CC: Ingo Molnar CC: Tejun Heo CC: Christoph Lameter CC: Benjamin Herrenschmidt

ipv6: reduce per device ICMP mib sizes

2011-05-19T20:21:22Z

ipv6 has per device ICMP SNMP counters, taking too much space because they use percpu storage. needed size per device is : (512+4)*sizeof(long)*number_of_possible_cpus*2 On a 32bit kernel, 16 possible cpus, this wastes more than 64kbytes of memory per ipv6 enabled network device, taken in vmalloc pool. Since ICMP messages are rare, just use shared counters (atomic_long_t) Per network space ICMP counters are still using percpu memory, we might also convert them to shared counters in a future patch. Signed-off-by: Eric Dumazet CC: Denys Fedoryshchenko Signed-off-by: David S. Miller

snmp: SNMP_UPD_PO_STATS_BH() always called from softirq

2011-03-22T01:12:54Z

We dont need to test if we run from softirq context, we definitely are. This saves few instructions in ip_rcv() & ip_rcv_finish() Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

net: kill unused macros from head file

2010-12-02T21:27:33Z

These macros have been defined for several years since v2.6.12-rc2（tracing by git）, but never be used. So remove them. Signed-off-by: Shan Wei Signed-off-by: David S. Miller