[lkml]   [2013]   [Nov]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH v2 2/2] x86: add prefetching to do_csum
Neil Horman <> writes:

> do_csum was identified via perf recently as a hot spot when doing
> receive on ip over infiniband workloads. After alot of testing and
> ideas, we found the best optimization available to us currently is to
> prefetch the entire data buffer prior to doing the checksum

On what CPU? Most modern CPUs should not have any trouble at all
prefetching a linear access.

Also for large buffers it is unlikely that all the prefetches
are actually executed, there is usually some limit.

As a minimum you would need:
- run it with a range of buffer sizes
- run this on a range of different CPUs and show no major regressions
- describe all of this actually in the description

But I find at least this patch very dubious.


-- -- Speaking for myself only

 \ /
  Last update: 2013-11-06 21:41    [W:0.106 / U:2.356 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site