From: David Mosberger <davidm@napali.hpl.hp.com>
To: linux-ia64@vger.kernel.org
Subject: [Linux-ia64] Re: strange performance behaviour with floats
Date: Mon, 24 Feb 2003 02:16:57 +0000 [thread overview]
Message-ID: <marc-linux-ia64-105590709805913@msgid-missing> (raw)
In-Reply-To: <marc-linux-ia64-105590709805910@msgid-missing>
>>>>> On Mon, 24 Feb 2003 13:01:10 +1100, Keith Owens <kaos@sgi.com> said:
Keith> Which loop needs unrolling? __delay generates
Keith> 2d0: 11 00 00 00 01 00 [MIB] nop.m 0x0
Keith> 2d6: 00 70 04 55 00 00 mov.i ar.lc=r14
Keith> 2dc: 00 00 00 20 nop.b 0x0;;
Keith> 2e0: 11 00 00 00 01 00 [MIB] nop.m 0x0
Keith> 2e6: 00 00 00 02 00 a0 nop.i 0x0
Keith> 2ec: 00 00 00 40 br.cloop.sptk.few 2e0 <calibrate_delay+0x100>;;
Keith> br.cloop is already a single bundle loop.
You're toying with me, right? ;-)
Let me say this again: you _don't_ want a single-cycle loop. You want
a 2-cycle loop that gets twice the work done as a 1-cycle loop. That
is, you'd want to decrement the loop counter by 2, compare it against
zero, and branch if it's not zero yet, all the while making sure you
get a 2-cycle loop.
--david
next prev parent reply other threads:[~2003-02-24 2:16 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-02-24 1:45 [Linux-ia64] Re: strange performance behaviour with floats Keith Owens
2003-02-24 1:50 ` David Mosberger
2003-02-24 2:01 ` Keith Owens
2003-02-24 2:16 ` David Mosberger [this message]
2003-02-24 2:25 ` Keith Owens
2003-02-24 19:12 ` David Mosberger
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=marc-linux-ia64-105590709805913@msgid-missing \
--to=davidm@napali.hpl.hp.com \
--cc=linux-ia64@vger.kernel.org \
/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