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From:   Roger Heflin <rogerheflin@gmail.com>
Date:   Wed, 7 Apr 2021 19:12:29 -0500
Message-ID: <CAAMCDecxjX5d20Ra7PVgsSM6xg3f2D5q=-x3eeFosfFfnbJxbg@mail.gmail.com>
Subject: Re: OT: Processor recommendation for RAID6
To:     Paul Menzel <pmenzel@molgen.mpg.de>
Cc:     Linux RAID <linux-raid@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>, it+linux-raid@molgen.mpg.de
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I ran some tests on a 4 intel socket box with files in tmpfs (gold
6152 I think) and with the files interleaved 4way (I think) got the
same speeds you got on your intels (roughly) with defaults.

I also tested on my 6 core/4500u ryzen and got almost the same
speed(slightly slower) as on your large ryzen boxes with many numa
nodes, so it has to be effectively only using a single numa node and a
single cpu.

I did test my 4500u ryzen machine with fewer cores enabled,  1 core
got 18M, 2 cores got 23M, and 3 got 32M so it did not appear scale
past 3 cores.

I also testing on an ancient a8-5600k and was almost the same speed as
the ryzen.

From the calls there must be a lot of reading memory.   And I got the
same speed using shm, using tmpfs, using tmpfs+hugepages and using
files on a disk that should have been in file cache.