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Date:   Mon, 26 Jul 2021 10:19:11 -0400
From:   "Theodore Ts'o" <tytso@mit.edu>
To:     Andres Freund <andres@anarazel.de>
Cc:     Matthew Wilcox <willy@infradead.org>,
        James Bottomley <James.Bottomley@hansenpartnership.com>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        linux-fsdevel@vger.kernel.org,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        "Darrick J. Wong" <djwong@kernel.org>,
        Christoph Hellwig <hch@lst.de>,
        Michael Larabel <Michael@michaellarabel.com>
Subject: Re: Folios give an 80% performance win
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On Sat, Jul 24, 2021 at 02:44:13PM -0700, Andres Freund wrote:
> The phoronix test uses postgres with only one relevant setting adjusted
> (increasing the max connection count). That will end up using a buffer pool of
> 128MB, no huge pages, and importantly is configured to aim for not more than
> 1GB for postgres' journal, which will lead to constant checkpointing. The test
> also only runs for 15 seconds, which likely isn't even enough to "warm up"
> (the creation of the data set here will take longer than the run).
> 
> Given that the dataset phoronix is using is about ~16GB of data (excluding
> WAL), and uses 256 concurrent clients running full tilt, using that limited
> postgres settings doesn't end up measuring something particularly interesting
> in my opinion.

Hi Andreas,

I tend to use the phoronix test suite for my performance runs when
testing ext4 changes simply because it's convenient.  Can you suggest
a better set configuration settings that I should perhaps use that
might give more "real world" numbers that you would find more
significant?

Thanks,

					- Ted