From: Ahmed Karaman <1892081@bugs.launchpad.net>
To: qemu-devel@nongnu.org
Subject: [Bug 1892081] [NEW] Performance improvement when using "QEMU_FLATTEN" with softfloat type conversions
Date: Tue, 18 Aug 2020 18:36:49 -0000 [thread overview]
Message-ID: <159777580973.2034.8843080316751302000.malonedeb@chaenomeles.canonical.com> (raw)
Public bug reported:
Attached below is a matrix multiplication program for double data
types. The program performs the casting operation "(double)rand()"
when generating random numbers.
This operation calls the integer to float softfloat conversion
function "int32_to_float_64".
Adding the "QEMU_FLATTEN" attribute to the function definition
decreases the instructions per call of the function by about 63%.
Attached are before and after performance screenshots from
KCachegrind.
** Affects: qemu
Importance: Undecided
Status: New
** Attachment added: "matmult_double.c"
https://bugs.launchpad.net/bugs/1892081/+attachment/5402577/+files/matmult_double.c
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1892081
Title:
Performance improvement when using "QEMU_FLATTEN" with softfloat type
conversions
Status in QEMU:
New
Bug description:
Attached below is a matrix multiplication program for double data
types. The program performs the casting operation "(double)rand()"
when generating random numbers.
This operation calls the integer to float softfloat conversion
function "int32_to_float_64".
Adding the "QEMU_FLATTEN" attribute to the function definition
decreases the instructions per call of the function by about 63%.
Attached are before and after performance screenshots from
KCachegrind.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1892081/+subscriptions
next reply other threads:[~2020-08-18 18:46 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-18 18:36 Ahmed Karaman [this message]
2020-08-18 18:37 ` [Bug 1892081] Re: Performance improvement when using "QEMU_FLATTEN" with softfloat type conversions Ahmed Karaman
2020-08-18 18:37 ` Ahmed Karaman
2020-10-18 20:26 ` Richard Henderson
2021-05-04 19:39 ` Thomas Huth
2021-06-23 17:32 ` Richard Henderson
2021-08-25 7:17 ` Thomas Huth
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=159777580973.2034.8843080316751302000.malonedeb@chaenomeles.canonical.com \
--to=1892081@bugs.launchpad.net \
--cc=qemu-devel@nongnu.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;
as well as URLs for NNTP newsgroup(s).