Messages in this thread | | | Date | Fri, 27 Jan 2006 23:58:14 +0100 | From | Eric Dumazet <> | Subject | Re: [patch 3/4] net: Percpufy frequently used variables -- proto.sockets_allocated |
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Ravikiran G Thirumalai a écrit : > On Fri, Jan 27, 2006 at 12:16:02PM -0800, Andrew Morton wrote: >> Ravikiran G Thirumalai <kiran@scalex86.org> wrote: >>> which can be assumed as not frequent. >>> At sk_stream_mem_schedule(), read_sockets_allocated() is invoked only >>> certain conditions, under memory pressure -- on a large CPU count machine, >>> you'd have large memory, and I don't think read_sockets_allocated would get >>> called often. It did not atleast on our 8cpu/16G box. So this should be OK >>> I think. >> That being said, the percpu_counters aren't a terribly successful concept >> and probably do need a revisit due to the high inaccuracy at high CPU >> counts. It might be better to do some generic version of vm_acct_memory() >> instead. > > AFAICS vm_acct_memory is no better. The deviation on large cpu counts is the > same as percpu_counters -- (NR_CPUS * NR_CPUS * 2) ...
Ah... yes you are right, I read min(16, NR_CPUS*2)
I wonder if it is not a typo... I mean, I understand the more cpus you have, the less updates on central atomic_t is desirable, but a quadratic offset seems too much...
Eric
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