linux-kernel - Re: [PATCH 2/3] mm/zswap: remove the memcpy if acomp is not asynchronous

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Date: Mon, 8 Jan 2024 14:36:41 -0800
From: Yosry Ahmed <yosryahmed@...gle.com>
To: Barry Song <21cnbao@...il.com>
Cc: herbert@...dor.apana.org.au, davem@...emloft.net, 
	akpm@...ux-foundation.org, ddstreet@...e.org, sjenning@...hat.com, 
	vitaly.wool@...sulko.com, linux-crypto@...r.kernel.org, chriscli@...gle.com, 
	chrisl@...nel.org, hannes@...xchg.org, linux-kernel@...r.kernel.org, 
	linux-mm@...ck.org, nphamcs@...il.com, zhouchengming@...edance.com, 
	Barry Song <v-songbaohua@...o.com>
Subject: Re: [PATCH 2/3] mm/zswap: remove the memcpy if acomp is not asynchronous

On Wed, Jan 3, 2024 at 1:50 AM Barry Song <21cnbao@...il.com> wrote:
>
> From: Barry Song <v-songbaohua@...o.com>
>
> Most compressors are actually CPU-based and won't sleep during
> compression and decompression. We should remove the redundant
> memcpy for them.
>
> Signed-off-by: Barry Song <v-songbaohua@...o.com>
> Tested-by: Chengming Zhou <zhouchengming@...edance.com>
> ---
>  mm/zswap.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/mm/zswap.c b/mm/zswap.c
> index ca25b676048e..36898614ebcc 100644
> --- a/mm/zswap.c
> +++ b/mm/zswap.c
> @@ -168,6 +168,7 @@ struct crypto_acomp_ctx {
>         struct crypto_wait wait;
>         u8 *buffer;
>         struct mutex mutex;
> +       bool is_async; /* if acomp can sleep */

As pointed out in patch 1, I think we should name this explicitly to
be about sleep-ability (e.g. sleepable or can_sleep).