linux-kernel - Re: [PATCH v5] zram: remove double compression logic

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Message-ID: <20220809130543.4dnh5aa3kdxbmzje@cab-wsm-0029881.sigma.sbrf.ru>
Date:   Tue, 9 Aug 2022 13:06:19 +0000
From:   Aleksey Romanov <AVRomanov@...rdevices.ru>
To:     Sergey Senozhatsky <senozhatsky@...omium.org>,
        "minchan@...nel.org" <minchan@...nel.org>
CC:     "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "ngupta@...are.org" <ngupta@...are.org>,
        "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
        "axboe@...omium.org" <axboe@...omium.org>,
        kernel <kernel@...rdevices.ru>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "mnitenko@...il.com" <mnitenko@...il.com>,
        Dmitry Rokosov <DDRokosov@...rdevices.ru>
Subject: Re: [PATCH v5] zram: remove double compression logic

Hi Sergey,

On Tue, Aug 09, 2022 at 09:41:22PM +0900, Sergey Senozhatsky wrote:
> On (22/05/05 12:44), Alexey Romanov wrote:
> > @@ -1975,7 +1954,6 @@ static int zram_add(void)
> >  	if (ZRAM_LOGICAL_BLOCK_SIZE == PAGE_SIZE)
> >  		blk_queue_max_write_zeroes_sectors(zram->disk->queue, UINT_MAX);
> >  
> > -	blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES, zram->disk->queue);
> 
> By the way, why did it remove QUEUE_FLAG_STABLE_WRITES bit?

Minchan asked me to add this change and this description:

"Since b09ab054b69b, zram has used QUEUE_FLAG_STABLE_WRITES to prevent
buffer change between 1st and 2nd memory allocations. Since we remove
second trial memory allocation logic, we could remove the STABLE_WRITES
flag because there is no change buffer to be modified under us"

This seems to be logical.

-- 
Thank you,
Alexey