linux-kernel - Re: [PATCH v4 2/6] mm/zswap: reuse dstmem when decompress

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Date: Sat, 27 Jan 2024 22:41:49 +0800
From: Barry Song <21cnbao@...il.com>
To: Herbert Xu <herbert@...dor.apana.org.au>
Cc: davem@...emloft.net, akpm@...ux-foundation.org, chriscli@...gle.com, 
	chrisl@...nel.org, ddstreet@...e.org, hannes@...xchg.org, linux-mm@...ck.org, 
	nphamcs@...il.com, sjenning@...hat.com, vitaly.wool@...sulko.com, 
	yosryahmed@...gle.com, zhouchengming@...edance.com, 
	linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org
Subject: Re: [PATCH v4 2/6] mm/zswap: reuse dstmem when decompress

On Thu, Jan 25, 2024 at 5:41 PM Herbert Xu <herbert@...dor.apana.org.au> wrote:
>
> On Wed, Jan 03, 2024 at 03:57:59PM +1300, Barry Song wrote:
> >
> > > We could certainly do that.  But I wonder if it might actually be
> > > better for you to allocate a second sync-only algorithm for such
> > > cases.  I'd like to see some real numbers.
> >
> > some hardware might want to use an accelerator to help offload CPU's
> > work. their drivers are working in async mode, for example, hisilicon
> > and intel.
> >
> > I don't have the exact number we can save by removing the redundant
> > memcpy, nor do i have a proper hardware to test and get the number.
> > As Chengming is actually working in zswap, i wonder if you can test
> > my patches and post some data?
>
> I don't have the hardware to test this.  Since you're proposing
> the change, please test it to ensure that we're not adding cruft
> to the API that's actually detrimental to performance.

Understood.
sorry for the grammatical errors, i was actually asking for
chengming's help for testing as
he had hardware and was actively working on optimizing  zswap.
and he has already tested and sent the performance data which I quoted
in the formal
patchset.

>
> Thanks,
> --
> Email: Herbert Xu <herbert@...dor.apana.org.au>
> Home Page: http://gondor.apana.org.au/~herbert/
> PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt


Thanks
Barry