From: Eric Dumazet <eric.dumazet@xxxxxxxxx> Date: Sat, 11 Jun 2011 07:45:51 +0200 > 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 <eric.dumazet@xxxxxxxxx> Looks good to me, applied, thanks Eric. -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
