From: Paolo Bonzini <pbonzini@redhat.com>
To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Stefan Weil <weil@mail.berlios.de>,
Anthony Liguori <aliguori@us.ibm.com>,
Christoph Egger <Christoph.Egger@amd.com>,
qemu-devel <qemu-devel@nongnu.org>,
Alexander Graf <agraf@suse.de>
Subject: Re: [Qemu-devel] [RFC][PATCH] signrom: Speed up checksum calculation
Date: Tue, 24 Jan 2012 09:39:53 +0100 [thread overview]
Message-ID: <4F1E6E59.6060405@redhat.com> (raw)
In-Reply-To: <4F1DA926.4000709@siemens.com>
On 01/23/2012 07:38 PM, Jan Kiszka wrote:
> nums=`od -A n -t u1 -v -N $size "$1"`
> -for i in ${nums}; do
> - # add each byte's value to sum
> - sum=`expr \( $sum + $i \) % 256`
> -done
> -
> -sum=$(( (256 - $sum) % 256 ))
We have a bashism here, so why not do
sum=$(( ($sum + $i) % 256 ))
and do the same with a one-line patch (two line if you change the header
to #!/bin/bash)? It should be just as fast as awk.
Paolo
prev parent reply other threads:[~2012-01-24 8:40 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-23 18:38 [Qemu-devel] [RFC][PATCH] signrom: Speed up checksum calculation Jan Kiszka
2012-01-23 19:16 ` Stefan Weil
2012-01-23 19:19 ` Jan Kiszka
2012-01-23 19:25 ` Stefan Weil
2012-01-23 20:08 ` Anthony Liguori
2012-01-23 20:32 ` Jan Kiszka
2012-01-23 20:37 ` Anthony Liguori
2012-01-23 21:32 ` Stefan Weil
2012-01-24 9:43 ` Andreas Färber
2012-01-24 8:18 ` Paolo Bonzini
2012-01-24 10:18 ` Christoph Egger
2012-01-24 8:39 ` Paolo Bonzini [this message]
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