Re: [PATCH v6 0/2] zswap: remove the memcpy if acomp is not sleepable

[Johannes Weiner <hannes@cmpxchg.org>]

On Thu, Feb 22, 2024 at 09:11:33PM +1300, Barry Song wrote:
> From: Barry Song <v-songbaohua@oppo.com>
> 
> In zswap, if we use zsmalloc, we cannot sleep while we map the
> compressed memory, so we copy it to a temporary buffer. By
> knowing the alg won't sleep can help zswap to avoid the
> memcpy.
> Thus we introduce an API in crypto to expose if acomp is async,
> and zswap can use it to decide if it can remove copying to the
> tmp buffer.
> 
> -v6:
>  * add acked-by of Herbert, Thanks!
>  * remove patch 3/3 from the series, as that one will go
>    through crypto
> 
> Barry Song (2):
>   crypto: introduce: acomp_is_async to expose if comp drivers might
>     sleep
>   mm/zswap: remove the memcpy if acomp is not sleepable
> 
>  include/crypto/acompress.h | 6 ++++++
>  mm/zswap.c                 | 6 ++++--
>  2 files changed, 10 insertions(+), 2 deletions(-)

Acked-by: Johannes Weiner <hannes@cmpxchg.org>

Looks good to me.

One small question: why cache is_sleepable in zswap instead of
checking acomp_is_async() directly? It doesn't look expensive.