Rick Jones a écrit :
Eric Dumazet wrote:
Stephen Hemminger a écrit :
On Thu, 01 Nov 2007 11:16:20 +0100
Eric Dumazet <[EMAIL PROTECTED]> wrote:
As done two years ago on IP route cache table (commit
22c047ccbc68fa8f3fa57f0e8f906479a062c426) , we can avoid using one
lock per hash bucket for the huge TCP/DCCP hash tables.
The TCP hashes are looked at with higher frequency than the route cache
yes?
It depends on the workload, but in general I would say the reverse.
On a typical x86_64 platform, this saves about 2MB or 4MB of ram,
for litle performance differences. (we hit a different cache line
for the rwlock, but then the bucket cache line have a better sharing
factor among cpus, since we dirty it less often)
Using a 'small' table of hashed rwlocks should be more than enough
to provide correct SMP concurrency between different buckets,
without using too much memory. Sizing of this table depends on
NR_CPUS and various CONFIG settings.
Something is telling me finding a 64 core system with a suitable
workload to try this could be a good thing. Wish I had one at my disposal.
If you find one, please give it to me when you finished playing^Wworking with
it :)
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