Re: [PATCH v7] mempool: test performance with larger bursts

[Thomas Monjalon <thomas@monjalon.net>]

13/09/2024 16:58, Morten Brørup:
> PING for apply.
> 
> Patch has 2 acks.
> And since it was signed off by a co-maintainer (myself),
> I don't think an ack from the other co-maintainer (Andrew) is required.
> Please correct me if I'm wrong?


It's not a matter of acks.

I feel we should reduce from 5 seconds to 1 second as part of this patch.
But seeing there is no more comments, I suppose I should apply this version.



> From: Morten Brørup [mailto:mb@smartsharesystems.com]
> > From: Bruce Richardson [mailto:bruce.richardson@intel.com]
> > > On Mon, Jun 10, 2024 at 10:56:00AM +0200, Morten Brørup wrote:
> > > > PING (again) for review.
> > > >
> > > > Many applications use bursts of more than 32 packets,
> > > > and some applications buffer more than 512 packets.
> > > >
> > > > This patch updates the mempool perf test accordingly.
> > > >
> > > > > From: Morten Brørup [mailto:mb@smartsharesystems.com]
> > > > > Sent: Thursday, 4 April 2024 11.27
> > > > >
> > > > > PING for review. This patch is relatively trivial.
> > > > >
> > > > > > From: Morten Brørup [mailto:mb@smartsharesystems.com]
> > > > > > Sent: Saturday, 2 March 2024 21.04
> > > > > >
> > > > > > Bursts of up to 64, 128 and 256 packets are not uncommon, so increase
> > > the
> > > > > > maximum tested get and put burst sizes from 32 to 256.
> > > > > > For convenience, also test get and put burst sizes of
> > > > > > RTE_MEMPOOL_CACHE_MAX_SIZE.
> > > > > >
> > > > > > Some applications keep more than 512 objects, so increase the maximum
> > > > > > number of kept objects from 512 to 32768, still in jumps of factor
> > four.
> > > > > > This exceeds the typical mempool cache size of 512 objects, so the
> > test
> > > > > > also exercises the mempool driver.
> > > > > >
> > > > > > Increased the precision of rate_persec calculation by timing the
> > actual
> > > > > > duration of the test, instead of assuming it took exactly 5 seconds.
> > > > > >
> > > > > > Added cache guard to per-lcore stats structure.
> > > > > >
> > > > > > Signed-off-by: Morten Brørup <mb@smartsharesystems.com>
> > > > > > Acked-by: Chengwen Feng <fengchengwen@huawei.com>
> > >
> > > This looks ok to me. However, the test itself takes a very long time to
> > > run, with 5 seconds per iteration. One suggest I have is to reduce the
> > > 5-seconds to 1-second - given we are looking at millions of iterations each
> > > time, the difference in results should not be that great, I'd hope.
> > 
> > The test duration annoys me too.
> > 
> > Reducing the duration of each iteration would make the test more sensitive to
> > short spikes of noise, e.g. from noisy neighbors in virtual environments.
> > Someone once decided that 5 seconds was a good duration, and I didn't want to
> > challenge that.
> > 
> > I also considered reducing the array of tested burst sizes, by jumping factor
> > four here too; but I assume that both 32, 64, 128 and 256 are popular max
> > burst sizes in applications, so I decided to keep them all, instead of
> > omitting 32 and 128 and only keeping 64 and 256 to represent full bursts.
> > 
> > > A very
> > > quick test of the delta on my end indicates variance in the first couple of
> > > results of a couple of %, just.
> > 
> > Thanks for the review and suggestions, though.
> > 
> > >
> > > With or without this suggestion.
> > >
> > > Acked-by: Bruce Richardson <bruce.richardson@intel.com>