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Re: Big TCG slowdown when using zstd with aarch64
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From: |
Daniel P . Berrangé |
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Subject: |
Re: Big TCG slowdown when using zstd with aarch64 |
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Date: |
Fri, 2 Jun 2023 11:14:26 +0100 |
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User-agent: |
Mutt/2.2.9 (2022-11-12) |
On Thu, Jun 01, 2023 at 11:06:42PM +0200, Juan Quintela wrote:
>
> Hi
>
> Before I continue investigating this further, do you have any clue what
> is going on here. I am running qemu-system-aarch64 on x86_64.
FYI, the trigger for this behaviour appears to be your recent change
to stats accounting in:
commit cbec7eb76879d419e7dbf531ee2506ec0722e825 (HEAD)
Author: Juan Quintela <quintela@redhat.com>
Date: Mon May 15 21:57:09 2023 +0200
migration/multifd: Compute transferred bytes correctly
In the past, we had to put the in the main thread all the operations
related with sizes due to qemu_file not beeing thread safe. As now
all counters are atomic, we can update the counters just after the
do the write. As an aditional bonus, we are able to use the right
value for the compression methods. Right now we were assuming that
there were no compression at all.
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Message-Id: <20230515195709.63843-17-quintela@redhat.com>
Before that commit the /aarch64/migration/multifd/tcp/plain/{none,zlib,zstd}
tests all took 21 seconds eachs.
After that commit the 'none' test takes about 3 seconds, and the zlib/zstd
test take about 1 second, except when zstd is suddenly very slow.
With regards,
Daniel
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