Received-SPF: pass (google.com: domain of linux-kernel+bounces-38298-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) client-ip=2604:1380:4601:e00::3;
Date: Thu, 25 Jan 2024 17:41:12 +0800
From: Herbert Xu <herbert@gondor.apana.org.au>
To: Barry Song <21cnbao@gmail.com>
Cc: davem@davemloft.net, akpm@linux-foundation.org, chriscli@google.com,
	chrisl@kernel.org, ddstreet@ieee.org, hannes@cmpxchg.org,
	linux-mm@kvack.org, nphamcs@gmail.com, sjenning@redhat.com,
	vitaly.wool@konsulko.com, yosryahmed@google.com,
	zhouchengming@bytedance.com, linux-kernel@vger.kernel.org,
	linux-crypto@vger.kernel.org
Subject: Re: [PATCH v4 2/6] mm/zswap: reuse dstmem when decompress
Message-ID: <ZbIsuN+bpHNX7CnL@gondor.apana.org.au>
References: <ZY1EnEefZsRTGYnP@gondor.apana.org.au>
 <20240103025759.523120-1-21cnbao@gmail.com>
 <20240103025759.523120-3-21cnbao@gmail.com>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20240103025759.523120-3-21cnbao@gmail.com>

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.

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