From: Michal Hocko <mhocko@suse.com>
To: Sebastiaan Meijer <meijersebastiaan@gmail.com>
Cc: akpm@linux-foundation.org, buddy.lumpkin@oracle.com,
hannes@cmpxchg.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, mgorman@suse.de, riel@surriel.com,
willy@infradead.org
Subject: Re: [RFC PATCH 1/1] vmscan: Support multiple kswapd threads per node
Date: Thu, 1 Oct 2020 14:30:32 +0200 [thread overview]
Message-ID: <20201001123032.GC22560@dhcp22.suse.cz> (raw)
In-Reply-To: <CANuy=C+JH7sZbMToWNNyWcKANbwSx5KLaiRBLHXBz6EU=JCABA@mail.gmail.com>
On Wed 30-09-20 21:27:12, Sebastiaan Meijer wrote:
> > yes it shows the bottleneck but it is quite artificial. Read data is
> > usually processed and/or written back and that changes the picture a
> > lot.
> Apologies for reviving an ancient thread (and apologies in advance for my lack
> of knowledge on how mailing lists work), but I'd like to offer up another
> reason why merging this might be a good idea.
>
> From what I understand, zswap runs its compression on the same kswapd thread,
> limiting it to a single thread for compression. Given enough processing power,
> zswap can get great throughput using heavier compression algorithms like zstd,
> but this is currently greatly limited by the lack of threading.
Isn't this a problem of the zswap implementation rather than general
kswapd reclaim? Why zswap doesn't do the same as normal swap out in a
context outside of the reclaim?
My recollection of the particular patch is dimm but I do remember it
tried to add more kswapd threads which would just paper over the problem
you are seein rather than solve it.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2020-10-01 12:30 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-30 19:27 [RFC PATCH 1/1] vmscan: Support multiple kswapd threads per node Sebastiaan Meijer
2020-10-01 12:30 ` Michal Hocko [this message]
2020-10-01 16:18 ` Sebastiaan Meijer
2020-10-02 7:03 ` Michal Hocko
2020-10-02 8:40 ` Mel Gorman
2020-10-02 13:53 ` Rik van Riel
2020-10-02 14:00 ` Matthew Wilcox
2020-10-02 14:29 ` Michal Hocko
-- strict thread matches above, loose matches on Subject: below --
2018-04-02 9:24 [RFC PATCH 0/1] mm: " Buddy Lumpkin
2018-04-02 9:24 ` [RFC PATCH 1/1] vmscan: " Buddy Lumpkin
2018-04-03 13:31 ` Michal Hocko
2018-04-03 19:07 ` Matthew Wilcox
2018-04-03 20:49 ` Buddy Lumpkin
2018-04-03 21:12 ` Matthew Wilcox
2018-04-04 10:07 ` Buddy Lumpkin
2018-04-05 4:08 ` Buddy Lumpkin
2018-04-11 6:37 ` Buddy Lumpkin
2018-04-11 3:52 ` Buddy Lumpkin
2018-04-03 20:13 ` Buddy Lumpkin
2018-04-11 3:10 ` Buddy Lumpkin
2018-04-12 13:23 ` Michal Hocko
[not found] ` <EB9E8FC6-8B02-4D7C-AA50-2B5B6BD2AF40@oracle.com>
2018-04-12 13:16 ` Michal Hocko
2018-04-17 3:02 ` Buddy Lumpkin
2018-04-17 9:03 ` Michal Hocko
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