From: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
To: "naohirot@fujitsu.com" <naohirot@fujitsu.com>,
"'Lucas A. M. Magalhaes'" <lamm@linux.ibm.com>,
Noah Goldstein <goldstein.w.n@gmail.com>,
"libc-alpha@sourceware.org" <libc-alpha@sourceware.org>
Subject: Re: [PATCH v3 2/5] benchtests: Add memset zero fill benchtest
Date: Tue, 21 Sep 2021 11:09:05 +0000 [thread overview]
Message-ID: <VE1PR08MB559995AB4ED1BCBDD0093C4F83A19@VE1PR08MB5599.eurprd08.prod.outlook.com> (raw)
In-Reply-To: <TYAPR01MB602551F15CF2C8048A2C1FE7DFA19@TYAPR01MB6025.jpnprd01.prod.outlook.com>
Hi Naohiro,
> In terms of the start size, 256B is chosen because __memset_generic
> (sysdeps/aarch64/memset.S) calls DC ZVA for zero fill from 256B, which
> code you committed [1].
> And I reported an interesting insight in the mail [2] that DC ZVA is
> slower than store instruction from 256B to 16KB on A64FX [3].
> So it seems valuable to measure the range from 256B to 16KB to see
> each CPU's behavior.
> What do you think?
As I've mentioned, this will never work using the current benchmark loop.
At size 256 your loop has only 1 timer tick... The only way to get any data
out is to increase the time taken per call. At 16K there are about 20 ticks so
it is still very inaccurate. By repeating the test thousands of times you can
some signal out (eg. 20% is 20 ticks, 80% is 21 gives ~20.8 ticks on average),
but that's impossible for smaller sizes.
So if you want to measure small sizes, you need to use a more accurate timing
loop.
Cheers,
Wilco
next prev parent reply other threads:[~2021-09-21 11:09 UTC|newest]
Thread overview: 83+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-13 8:22 [PATCH] benchtests: Add memset zero fill benchmark tests Naohiro Tamura
2021-07-13 13:50 ` Lucas A. M. Magalhaes
2021-07-20 6:31 ` [PATCH v2 0/5] " Naohiro Tamura
2021-08-05 7:47 ` [PATCH v3 0/5] benchtests: Add memset zero fill benchmark test Naohiro Tamura
2021-08-05 7:49 ` [PATCH v3 1/5] benchtests: Enable scripts/plot_strings.py to read stdin Naohiro Tamura
2021-08-05 7:56 ` Siddhesh Poyarekar
2021-09-08 1:46 ` naohirot
2021-09-08 12:56 ` Siddhesh Poyarekar
2021-09-09 0:22 ` naohirot
2021-09-13 3:45 ` Siddhesh Poyarekar
2021-08-05 7:50 ` [PATCH v3 2/5] benchtests: Add memset zero fill benchtest Naohiro Tamura
2021-09-08 2:03 ` naohirot
2021-09-10 20:40 ` Lucas A. M. Magalhaes
2021-09-13 0:53 ` naohirot
2021-09-13 14:05 ` Lucas A. M. Magalhaes
2021-09-14 0:38 ` [PATCH v4] " Naohiro Tamura
2021-09-14 0:44 ` [PATCH v3 2/5] " naohirot
2021-09-14 14:02 ` Wilco Dijkstra
2021-09-15 8:24 ` naohirot
2021-09-21 1:27 ` naohirot
2021-09-21 11:09 ` Wilco Dijkstra [this message]
2021-09-22 1:05 ` [PATCH v5] " Naohiro Tamura
2023-02-09 17:23 ` Carlos O'Donell
2023-02-10 1:26 ` Siddhesh Poyarekar
2021-09-22 1:07 ` [PATCH v3 2/5] " naohirot
2021-09-28 1:40 ` naohirot
2021-09-30 0:55 ` Tamura, Naohiro/田村 直�
2021-10-18 12:57 ` Lucas A. M. Magalhaes
2021-10-20 13:44 ` Wilco Dijkstra
2021-10-20 15:35 ` Lucas A. M. Magalhaes
2021-10-20 17:47 ` Wilco Dijkstra
2021-10-22 13:08 ` Lucas A. M. Magalhaes
2021-08-05 7:51 ` [PATCH v3 3/5] benchtests: Remove redundant assert.h Naohiro Tamura
2021-09-08 1:59 ` naohirot
2021-09-13 3:36 ` Siddhesh Poyarekar
2021-08-05 7:51 ` [PATCH v3 4/5] benchtests: Fix validate_benchout.py exceptions Naohiro Tamura
2021-09-08 1:55 ` naohirot
2021-09-13 3:42 ` Siddhesh Poyarekar
2021-09-13 3:50 ` Siddhesh Poyarekar
2021-09-13 13:44 ` [PATCH v4] " Naohiro Tamura
2021-09-15 3:23 ` Siddhesh Poyarekar
2021-09-16 1:12 ` naohirot
2021-09-16 1:41 ` Siddhesh Poyarekar
2021-09-16 2:23 ` [PATCH v5] " Naohiro Tamura
2021-09-16 3:48 ` Siddhesh Poyarekar
2021-09-16 5:23 ` naohirot
2021-09-16 2:26 ` [PATCH v4] " naohirot
2021-09-13 13:46 ` [PATCH v3 4/5] " naohirot
2021-08-05 7:52 ` [PATCH v3 5/5] config: Rename HAVE_BUILTIN_MEMSET macro Naohiro Tamura
2021-08-11 20:34 ` Adhemerval Zanella
2021-07-20 6:34 ` [PATCH v2 1/5] benchtests: Enable scripts/plot_strings.py to read stdin Naohiro Tamura
2021-07-20 6:35 ` [PATCH v2 2/5] benchtests: Add memset zero fill benchtest Naohiro Tamura
2021-07-20 16:48 ` Noah Goldstein
2021-07-21 12:56 ` naohirot
2021-07-21 13:07 ` naohirot
2021-07-21 18:14 ` Noah Goldstein
2021-07-21 19:17 ` Wilco Dijkstra
2021-07-26 8:42 ` naohirot
2021-07-26 11:15 ` Wilco Dijkstra
2021-07-27 2:24 ` naohirot
2021-07-27 17:26 ` Wilco Dijkstra
2021-07-28 7:27 ` naohirot
2021-08-04 9:11 ` naohirot
2021-07-26 8:39 ` naohirot
2021-07-26 17:22 ` Noah Goldstein
2021-07-20 6:35 ` [PATCH v2 3/5] benchtests: Add a script to convert benchout string JSON to CSV Naohiro Tamura
2021-07-21 2:41 ` naohirot
2021-07-27 20:17 ` Joseph Myers
2021-07-29 1:56 ` naohirot
2021-07-29 4:42 ` Siddhesh Poyarekar
2021-07-30 7:05 ` naohirot
2021-07-31 10:47 ` Siddhesh Poyarekar
2021-07-20 6:36 ` [PATCH v2 4/5] benchtests: Remove redundant assert.h Naohiro Tamura
2021-07-20 6:37 ` [PATCH v2 5/5] benchtests: Fix validate_benchout.py exceptions Naohiro Tamura
2021-07-26 8:34 ` [PATCH] config: Remove HAVE_BUILTIN_MEMSET macro Naohiro Tamura
2021-07-26 8:48 ` naohirot
2021-07-26 8:49 ` Andreas Schwab
2021-07-26 9:42 ` naohirot
2021-07-26 9:51 ` Andreas Schwab
2021-07-26 13:16 ` naohirot
2021-07-26 8:35 ` [PATCH] benchtests: Add a script to merge two benchout string files Naohiro Tamura
2021-07-27 20:51 ` Joseph Myers
2021-07-30 7:04 ` naohirot
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