linux-kernel - Re: [PATCH v2] zram: easy the allocation of zcomp

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Message-ID: <41226c84-e780-4408-b7d2-bd105f4834f5@kernel.dk>
Date: Tue, 6 Feb 2024 19:40:17 -0700
From: Jens Axboe <axboe@...nel.dk>
To: Sergey Senozhatsky <senozhatsky@...omium.org>,
 Barry Song <21cnbao@...il.com>, Minchan Kim <minchan@...nel.org>,
 Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
 zhengtangquan@...o.com, Barry Song <v-songbaohua@...o.com>
Subject: Re: [PATCH v2] zram: easy the allocation of zcomp_strm's buffers
 through vmalloc

On 2/6/24 6:44 PM, Sergey Senozhatsky wrote:
> On (24/02/07 09:25), Barry Song wrote:
>> From: Barry Song <v-songbaohua@...o.com>
>>
>> Firstly, there is no need to keep zcomp_strm's buffers contiguous
>> physically.
>>
>> Secondly, The recent mTHP project has provided the possibility to
>> swapout and swapin large folios. Compressing/decompressing large
>> blocks can hugely decrease CPU consumption and improve compression
>> ratio. This requires us to make zRAM support the compression and
>> decompression for large objects.
>> With the support of large objects in zRAM of our out-of-tree code,
>> we have observed many allocation failures during CPU hotplug as
>> large objects need larger buffers. So this change is also more
>> future-proof once we begin to bring up multiple sizes in zRAM.
>>
>> Signed-off-by: Barry Song <v-songbaohua@...o.com>
> 
> Reviewed-by: Sergey Senozhatsky <senozhatsky@...omium.org>
> 
> Note:
> Taking it in NOT because of the out-of-tree code (we don't really
> do that), but because this is executed from CPU offline/online
> paths, which can happen on devices with fragmented memory (a valid
> concern IMHO).
> 
> Minchan, if you have any objections, please chime in.

Not Minchan, but I do have an issue with the title of the commit, it
doesn't make any sense. Can the maintainer please re-write that to be
something that is appropriate and actually describes what the patch
does?

-- 
Jens Axboe