From: Janne Grunau <j@jannau.net>
To: Loic Dachary <loic@dachary.org>
Cc: Kevin Greenan <kmgreen2@gmail.com>,
Ceph Development <ceph-devel@vger.kernel.org>
Subject: Re: gf_unit 16 A -1 -m SPLIT 16 4 -r ALTMAP - failure
Date: Mon, 2 Feb 2015 22:14:57 +0100 [thread overview]
Message-ID: <20150202211457.GK2734@jannau.net> (raw)
In-Reply-To: <54B16763.7070602@dachary.org>
On 2015-01-10 18:54:43 +0100, Loic Dachary wrote:
> Hi Kevin & Janne,
>
> The test gf_unit 16 A -1 -m SPLIT 16 4 -r ALTMAP - fails on the current gf-complete master. The first commit where it fails is
>
> commit 474010a91d35fef5ca7dea77205b6a5c7e68c3e9
> Author: Janne Grunau <j@jannau.net>
> Date: Wed Sep 17 16:10:25 2014 +0200
>
> arm: NEON optimisations for gf_w16
>
> Optimisations for the 4,16 split table region multiplications.
>
> Selected time_tool.sh 16 -A -B results for a 1.7 GHz cortex-a9:
> Region Best (MB/s): 532.14 W-Method: 16 -m SPLIT 16 4 -r SIMD -
> Region Best (MB/s): 212.34 W-Method: 16 -m SPLIT 16 4 -r NOSIMD -
> Region Best (MB/s): 801.36 W-Method: 16 -m SPLIT 16 4 -r SIMD -r ALTMAP -
> Region Best (MB/s): 93.20 W-Method: 16 -m SPLIT 16 4 -r NOSIMD -r ALTMAP -
> Region Best (MB/s): 273.99 W-Method: 16 -m SPLIT 16 8 -
> Region Best (MB/s): 270.81 W-Method: 16 -m SPLIT 8 8 -
> Region Best (MB/s): 70.42 W-Method: 16 -m COMPOSITE 2 - -
> Region Best (MB/s): 393.54 W-Method: 16 -m COMPOSITE 2 - -r ALTMAP -
>
> but the test did exit(0) on error instead of exit(1) and we failed to notice.
>
> gf_unit 16 A -1 -m SPLIT 16 4 -r ALTMAP -
> Args: 16 A -1 -m SPLIT 16 4 -r ALTMAP - / size (bytes): 524428
> Problem with region multiply (all values in hex):
> Target address base: 0x8fd08e. Word 0x1 of 0x1fee. Xor: 0
> Value: 2
> Original source word: d00a
> Product word: a000
> It should be: b01f
>
> Do you have an idea why this happens ? For the record here is the bisect command I used:
yes, it happens because the arm code is incomplete and bogus. I did the
arm64 code first and then ported it to arm. This function uses arm64
specific instructions and thus needed a port to arm. The arm version
misses several computation steps. I guess I trusted the results of the
unit tests and didn't looked at gf_unit output on arm.
I'll send a fix tomorrow.
Janne
next prev parent reply other threads:[~2015-02-02 21:25 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-10 17:54 gf_unit 16 A -1 -m SPLIT 16 4 -r ALTMAP - failure Loic Dachary
2015-01-10 17:58 ` Loic Dachary
2015-02-02 21:14 ` Janne Grunau [this message]
2015-02-02 21:47 ` Loic Dachary
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