linux-kernel - Re: [PATCH V3] KSM: allow dedup all tasks memory

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Message-ID: <20181113014928.GH21824@bombadil.infradead.org>
Date:   Mon, 12 Nov 2018 17:49:28 -0800
From:   Matthew Wilcox <willy@...radead.org>
To:     Timofey Titovets <timofey.titovets@...esis.ru>
Cc:     linux-kernel@...r.kernel.org,
        Timofey Titovets <nefelim4ag@...il.com>, linux-mm@...ck.org,
        linux-doc@...r.kernel.org
Subject: Re: [PATCH V3] KSM: allow dedup all tasks memory

On Tue, Nov 13, 2018 at 02:13:44AM +0300, Timofey Titovets wrote:
> Some numbers from different not madvised workloads.
> Formulas:
>   Percentage ratio = (pages_sharing - pages_shared)/pages_unshared
>   Memory saved = (pages_sharing - pages_shared)*4/1024 MiB
>   Memory used = free -h
> 
>   * Name: My working laptop
>     Description: Many different chrome/electron apps + KDE
>     Ratio: 5%
>     Saved: ~100  MiB
>     Used:  ~2000 MiB

Your _laptop_ saves 100MB of RAM?  That's extraordinary.  Essentially
that's like getting an extra 100MB of page cache for free.  Is there
any observable slowdown?  I could even see there being a speedup (due
to your working set being allowed to be 5% larger)

I am now a big fan of this patch and shall try to give it the review
that it deserves.