linux-kernel - Re: [PATCHv4 00/12] dmapool enhancements

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Message-ID: <Y9MaaZDY5BrgUwkm@kbusch-mbp.dhcp.thefacebook.com>
Date:   Thu, 26 Jan 2023 17:27:21 -0700
From:   Keith Busch <kbusch@...nel.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Keith Busch <kbusch@...a.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, willy@...radead.org, hch@....de,
        tonyb@...ernetics.com, kernel-team@...a.com
Subject: Re: [PATCHv4 00/12] dmapool enhancements

On Thu, Jan 26, 2023 at 02:22:09PM -0800, Andrew Morton wrote:
> On Thu, 26 Jan 2023 13:51:13 -0800 Keith Busch <kbusch@...a.com> wrote:
> 
> > Time spent in dma_pool alloc/free increases linearly with the number of
> > pages backing the pool. We can reduce this to constant time with minor
> > changes to how free pages are tracked.
> 
> Do we have any performance testing results for realistic workloads?

Yes, I mentioned this a little in patch 11, profiling with nvme with high-depth
dmapool allocating workloads. Results really depend on your environment, so
YMMV, but I was able to observe time spent in dma_pool_{alloc,free}() reduced
by half.