Re: page fault scalability patch V11 [0/7]: overview

William Lee Irwin III
2004-11-22T22:43:33Z

On Sat, 20 Nov 2004, William Lee Irwin III wrote:
>> I'm not particularly "stuck on" the per-cpu business, it was merely the
>> most obvious method of splitting the RSS counter without catastrophes
>> elsewhere. Robin Holt's 2.4 performance studies actually show that
>> splitting the counter is not even essential.

On Mon, Nov 22, 2004 at 09:44:02AM -0800, Christoph Lameter wrote:
> There is no problem moving back to the atomic approach that is if it is
> okay to also make anon_rss atomic. But its a pretty significant
> performance hit (comparison with some old data from V4 of patch which
> makes this data a bit suspect since the test environment is likely
> slightly different. I should really test this again. Note that the old
> performance test was only run 3 times instead of 10):
> atomic vs. sloppy rss performance 64G allocation:

The specific patches you compared matter a great deal as there are
implementation blunders (e.g. poor placement of counters relative to
->mmap_sem) that can ruin the results. URL's to the specific patches
would rule out that source of error.

-- wli