From: Ahmed Karaman <1892081@bugs.launchpad.net>
To: qemu-devel@nongnu.org
Subject: [Bug 1892081] Re: Performance improvement when using "QEMU_FLATTEN" with softfloat type conversions
Date: Tue, 18 Aug 2020 18:37:25 -0000 [thread overview]
Message-ID: <159777584559.1974.4681080495054905457.malone@chaenomeles.canonical.com> (raw)
In-Reply-To: 159777580973.2034.8843080316751302000.malonedeb@chaenomeles.canonical.com
** Attachment added: "after.png"
https://bugs.launchpad.net/qemu/+bug/1892081/+attachment/5402579/+files/after.png
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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 prev parent 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 [Bug 1892081] [NEW] Performance improvement when using "QEMU_FLATTEN" with softfloat type conversions Ahmed Karaman
2020-08-18 18:37 ` [Bug 1892081] " Ahmed Karaman
2020-08-18 18:37 ` Ahmed Karaman [this message]
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
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