From: Christoph Hellwig <hch@lst.de>
To: Eric Biggers <ebiggers@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org
Subject: Re: [PATCH 2/2] xor/kunit: add a benchmark
Date: Thu, 18 Jun 2026 11:22:24 +0200 [thread overview]
Message-ID: <20260618092224.GB17530@lst.de> (raw)
In-Reply-To: <20260617171448.GD785086@google.com>
On Wed, Jun 17, 2026 at 05:14:48PM +0000, Eric Biggers wrote:
> The #ifdef can be avoided using kunit_skip(), as the crypto and CRC
> tests do:
>
> if (!IS_ENABLED(CONFIG_XOR_BENCHMARK))
> kunit_skip(test, "not enabled");
I saw that, but what's the point or just not compiling it?
> > + static_assert(ARRAY_SIZE(len_to_test) == 2);
> > + kunit_info(test, "%3u disks:\t%5llu GB/s\t%5llu GB/s\n",
> > + nr, speed[0], speed[1]);
>
> As mentioned in the other thread, this measures the speed at which the
> source data is consumed, which differs from the code in
> lib/raid/xor/xor-core.c that measures the speed at which the destination
> data is produced. Probably best to make them consistent.
The throughput for the generated parity isn't very interesting. It is
the overall throughput that determines the performance. And yes,
the selection benchmark is a complete mess - the single disk XOR is
not a relevant performance metric.
prev parent reply other threads:[~2026-06-18 9:22 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-17 5:44 xor: add a kunit benchmark Christoph Hellwig
2026-06-17 5:44 ` [PATCH 1/2] xor/kunit: fix a spelling error Christoph Hellwig
2026-06-17 5:44 ` [PATCH 2/2] xor/kunit: add a benchmark Christoph Hellwig
2026-06-17 6:00 ` sashiko-bot
2026-06-17 17:14 ` Eric Biggers
2026-06-18 9:22 ` Christoph Hellwig [this message]
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