linux-kernel - Re: [PATCH v3 7/7] zram: writeback throttle

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Message-ID: <20181203024146.GA149587@google.com>
Date:   Mon, 3 Dec 2018 11:41:46 +0900
From:   Minchan Kim <minchan@...nel.org>
To:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Joey Pabalinas <joeypabalinas@...il.com>
Subject: Re: [PATCH v3 7/7] zram: writeback throttle

On Mon, Dec 03, 2018 at 11:30:40AM +0900, Sergey Senozhatsky wrote:
> On (12/03/18 08:18), Minchan Kim wrote:
> > 
> > Per andrew's comment:
> > https://lkml.org/lkml/2018/11/27/156
> > 
> > I need to fix it to represent 4K always.
> 
> Aha.
> 
> Then we need to increase bd_writes PAGE_SIZE/4K times in writeback_store()?
> 
>    wb_count = atomic64_inc_return(&zram->stats.bd_writes);
>    ...
>    if (wb_limit != 0 && wb_count >= wb_limit)
>        zram->stop_writeback = true;
> 
> bd_wb_limit is in 4K units; but in writeback_store() we alloc a full page
> and write it to the backing device. So the actual number of written bytes
> can be larger on systems with page_size > 4K. Right?

Hey Sergey,

I changed interface in recent version v4. I belive it would be more
straigtforward for user. Could you review it?

Thanks!