From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: shurdeek@panorama.sth.ac.at (Peter Surda)
Cc: linux-kernel@vger.kernel.org
Subject: Re: memcpy to videoram eats too much CPU on ATI cards (cache trashing?)
Date: Mon, 27 Aug 2001 20:22:40 +0100 (BST) [thread overview]
Message-ID: <E15bRy4-0004Va-00@the-village.bc.nu> (raw)
In-Reply-To: <20010827201351.H17545@shurdeek.cb.ac.at> from "Peter Surda" at Aug 27, 2001 08:13:51 PM
> cause any CPU load (or more precisely, non-measurable load). However, with
> mach64 and r128, it DOES. I did some more research.
Makes sense
> memcpy-ing 380kB at 25fps takes about 5ms per frame and causes X to eat 1% cpu
> time (time measurements were done by tsc)
> memcpy-ing 760kB at 25fps takes about 11ms per frame, but instead of eating
> 2% CPU time, it eats 35% (yes, that's 35 times more)
So presumably at this bandwidth you are beginning collide with the graphics
controllers and it will stall your cycles, at which point its going to stall
the CPU so effectively eat CPU time
Sounds like a reasonable explanation to me
next prev parent reply other threads:[~2001-08-27 19:20 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-08-27 18:13 memcpy to videoram eats too much CPU on ATI cards (cache trashing?) Peter Surda
2001-08-27 19:22 ` Alan Cox [this message]
2001-08-27 21:40 ` Rogier Wolff
2001-08-27 22:01 ` Peter Surda
2001-09-06 6:18 ` (solved) memcpy to videoram eats too much CPU on ATI cards Peter Surda
2001-09-06 11:37 ` Daniel Egger
2001-09-06 13:10 ` Peter Surda
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=E15bRy4-0004Va-00@the-village.bc.nu \
--to=alan@lxorguk.ukuu.org.uk \
--cc=linux-kernel@vger.kernel.org \
--cc=shurdeek@panorama.sth.ac.at \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).