linux-kernel - Re: [PATCH v2] mm: add zblock allocator

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Message-ID: <3f013184c80e254585b56c5f16b7e778@beldev.am>
Date: Tue, 08 Apr 2025 13:20:11 +0400
From: Igor Belousov <igor.b@...dev.am>
To: Nhat Pham <nphamcs@...il.com>
Cc: vitaly.wool@...sulko.se, Johannes Weiner <hannes@...xchg.org>,
 linux-mm@...ck.org, akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
 Shakeel Butt <shakeel.butt@...ux.dev>
Subject: Re: [PATCH v2] mm: add zblock allocator


>> >> >>> Do you have zswap/zswapped meminfo metrics from these tests?
>> >> >> Yep, and those look somewhat similar:
>> >> >>  - zblock:
>> >> >> Zswap:            234128 kB
>> >> >> Zswapped:         733216 kB
>> >> >> -  zsmalloc:
>> >> >> Zswap:            286080 kB
>> >> >> Zswapped:         774688 kB
>> >> >
>> >> > I tested the kernel build on a 4-core virtual machine with allocated 4
>> >> > GB RAM running on a Ryzen 9.
>> >> >
>> >> > The results are the following:
>> >> [...]
>> >>
>> >> Now what's funny is that when I tried to compare how 32 threaded build
>> >> would behave on a 8-core VM I couldn't do it because it OOMs with
>> >> zsmalloc as zswap backend. With zblock it doesn't, though, and the
>> >> results are:
>> >> real    12m14.012s
>> >> user    39m37.777s
>> >> sys     14m6.923s
>> >> Zswap:            440148 kB
>> >> Zswapped:         924452 kB
>> >> zswpin 594812
>> >> zswpout 2802454
>> >> zswpwb 10878
>> >>
>> >> /Igor
>> >
>> > May I ask what compression algorithm you are using?
>> 
>> It's LZ4 for all the test runs.
> 
> Can you try zstd and let me know how it goes :)

Sure. zstd/8 cores/make -j32:

zsmalloc:
real	7m36.413s
user	38m0.481s
sys	7m19.108s
Zswap:            211028 kB
Zswapped:         925904 kB
zswpin 397851
zswpout 1625707
zswpwb 5126

zblock:
real	7m55.009s
user	39m23.147s
sys	7m44.004s
Zswap:            253068 kB
Zswapped:         919956 kB
zswpin 456843
zswpout 2058963
zswpwb 3921

>> > And does the zswpwb come from zswap shrinker?
>> 
>> Haven't looked into that, to be honest.
> 
> Can you check:
> 
> /sys/module/zswap/parameters/shrinker_enabled

It's 'Y' so the answer is yes.

/Igor