On 07/15/2015 11:39 AM, Amos Jeffries wrote:
On 16/07/2015 1:51 a.m., Stakres wrote:
Hi Fred,
tests from my side:
DISKD with TCP_HIT objects: 564KB/s with wget, the same url you have tested.
AUFS with TCP_HITS objects: 47.8M/s, same wget, same squid, same url, same
all.
Wget with AUFS:
Length: 10095849 (9.6M) [application/x-msdos-program]
Saving to: `youtube_downloader_hd_setup-2.9.9.23.exe'
100%[======================================>] 10,095,849 47.9M/s in 0.2s
2015-07-15 15:48:29 (47.9 MB/s) - `youtube_downloader_hd_setup-2.9.9.23.exe'
saved
All,
We have switched some ISPs from DISKD to AUFS this morning, the "queue
congestion" appears at the begining then disappears from the cache.log. For
how long, nobody knows...
Doh. Sorry its been so long I had forgotten one detail ...
Squid AUFS starts with a relatively short I/O queue length (8 entries)
and auto-grows it as needed by doubling the limit and displaying the
congestion message. On any busy proxy this can be seen for a while after
startup, then possibly during the first traffic peak after that. It is
not a problem unless it keeps growing indefinitely or appears suddenly
without a matching traffic spike (possible sign of disk failure).
I'm applying a patch to raise the baseline queue length from 8 to 8K,
and reporting in each message what the limit was changed to. That should
get rid of a dozen entries in your logs, and help show whats going on in
the remainder.
Since you will modify the log message from
WARNING - Queue congestion
to something like
INFO - the I/O queue lenght was X and has been doubled to 2X because of the current I/O load.
admins will understand _much_ better what is going on.
I think that changing the baseline to 8K is not required since the queue congestion
warning is normally seen only a few times, so the baseline value of 8 is doubled
only a few times.
A new baseline value of 256 (5 doublings) makes sense to me since most disks have
a hardware queue depth of 256.
For those systems where many disks are tortured with I/O the doubling will appear
a few (log2(#disks)) times.
Marcus
Amos
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