From: Florian Weimer <fw@deneb.enyo.de>
To: Wilco Dijkstra via Libc-alpha <libc-alpha@sourceware.org>
Cc: Szabolcs Nagy <Szabolcs.Nagy@arm.com>,
Wilco Dijkstra <Wilco.Dijkstra@arm.com>
Subject: Re: [PATCH 0/5] Added optimized memcpy/memmove/memset for A64FX
Date: Mon, 12 Apr 2021 20:53:54 +0200 [thread overview]
Message-ID: <87tuobibb1.fsf@mid.deneb.enyo.de> (raw)
In-Reply-To: <VE1PR08MB559991EE24FFB21C1258B71783709@VE1PR08MB5599.eurprd08.prod.outlook.com> (Wilco Dijkstra via Libc-alpha's message of "Mon, 12 Apr 2021 12:52:05 +0000")
* Wilco Dijkstra via Libc-alpha:
> 5. Odd prefetches
>
> I have a hard time believing first prefetching the data to be
> written, then clearing it using DC ZVA (???), then prefetching the
> same data a 2nd time, before finally write the loaded data is
> helping performance... Generally hardware prefetchers are able to
> do exactly the right thing since memcpy is trivial to prefetch. So
> what is the performance gain of each prefetch/clear step? What is
> the difference between memcpy and memmove performance (given memmove
> doesn't do any of this)?
Another downside is exposure of latent concurrency bugs:
G1: Phantom zeros in cardtable
<https://bugs.openjdk.java.net/browse/JDK-8039042>
I guess the CPU's heritage is shining through here. 8-)
next prev parent reply other threads:[~2021-04-12 18:54 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-12 12:52 [PATCH 0/5] Added optimized memcpy/memmove/memset for A64FX Wilco Dijkstra via Libc-alpha
2021-04-12 18:53 ` Florian Weimer [this message]
2021-04-13 12:07 ` naohirot
2021-04-14 16:02 ` Wilco Dijkstra via Libc-alpha
2021-04-15 12:20 ` naohirot
2021-04-20 16:00 ` Wilco Dijkstra via Libc-alpha
2021-04-27 11:58 ` naohirot
2021-04-29 15:13 ` Wilco Dijkstra via Libc-alpha
2021-04-30 15:01 ` Szabolcs Nagy via Libc-alpha
2021-04-30 15:23 ` Wilco Dijkstra via Libc-alpha
2021-04-30 15:30 ` Florian Weimer via Libc-alpha
2021-04-30 15:40 ` Wilco Dijkstra via Libc-alpha
2021-05-04 7:56 ` Szabolcs Nagy via Libc-alpha
2021-05-04 10:17 ` Florian Weimer via Libc-alpha
2021-05-04 10:38 ` Wilco Dijkstra via Libc-alpha
2021-05-04 10:42 ` Szabolcs Nagy via Libc-alpha
2021-05-04 11:07 ` Florian Weimer via Libc-alpha
2021-05-06 10:01 ` naohirot
2021-05-06 14:26 ` Szabolcs Nagy via Libc-alpha
2021-05-06 15:09 ` Florian Weimer via Libc-alpha
2021-05-06 17:31 ` Wilco Dijkstra via Libc-alpha
2021-05-07 12:31 ` naohirot
2021-04-19 2:51 ` naohirot
2021-04-19 14:57 ` Wilco Dijkstra via Libc-alpha
2021-04-21 10:10 ` naohirot
2021-04-21 15:02 ` Wilco Dijkstra via Libc-alpha
2021-04-22 13:17 ` naohirot
2021-04-23 0:58 ` naohirot
2021-04-19 12:43 ` naohirot
2021-04-20 3:31 ` naohirot
2021-04-20 14:44 ` Wilco Dijkstra via Libc-alpha
2021-04-27 9:01 ` naohirot
2021-04-20 5:49 ` naohirot
2021-04-20 11:39 ` Wilco Dijkstra via Libc-alpha
2021-04-27 11:03 ` naohirot
2021-04-23 13:22 ` naohirot
-- strict thread matches above, loose matches on Subject: below --
2021-03-17 2:28 Naohiro Tamura
2021-03-29 12:03 ` Szabolcs Nagy via Libc-alpha
2021-05-10 1:45 ` naohirot
2021-05-14 13:35 ` Szabolcs Nagy via Libc-alpha
2021-05-19 0:11 ` naohirot
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