Re: [squid-users] Squid high bandwidth IO issue (ramdisk SSD)

Well I'm seeing that the CPU is taking a lot of time waiting for outstanding
disk I/O request.
Adi

Adrian Chadd-3 wrote:
>
> Are you seeing high IO wait CPU use, or high IO wait times on IO?
>
>
>
> Adrian
>
> 2009/8/2 smaugadi <adi_at_binat.net.il>:
>>
>> Dear Adrian,
>> Well my conclusion that this is an IO problem came from the fact that I
>> see
>> huge IO waits as the volume of traffic increase (with tools such as
>> mpstat),
>> when using ramdisk there is no such issue.
>> I have configured the SSD drive with ext2, no journal, noatime. Used the
>> “noop” I/O scheduler.
>> In /etc/fstab
>> /dev/sdb1               /cache                  ext2 defaults,noatime 1 2
>>
>> hdparm results:
>> hdparm -t /dev/sdb1
>>
>> /dev/sdb1:
>>  Timing buffered disk reads:  304 MB in  3.01 seconds = 100.93 MB/sec
>> ----
>> hdparm -T /dev/sdb1
>>
>> /dev/sdb1:
>>  Timing cached reads:   4192 MB in  2.00 seconds = 2096.58 MB/sec
>>
>> Any ideas?
>>
>> Regards.
>>
>>
>>
>> Adrian Chadd-3 wrote:
>>>
>>> 2009/8/2 smaugadi <adi_at_binat.net.il>:
>>>>
>>>> Dear Adrian,
>>>> During the implementation we encountered issues with all kind of
>>>> variables
>>>> such as:
>>>> Limit of file descriptors (now the squid is using 204800).
>>>> TCP port range was low (increased to 1024 65535) TCP timers (changed
>>>> them)
>>>> The ip_conntrack and hash size were low (now 524288 262144
>>>> respectively)
>>>>
>>>> Now we are at a point that IO is the only issue.
>>>
>>> What profiling have you done to support that? For example, one of the
>>> issues I had which looked like IO performance was actually because the
>>> controller was completely unhappy. Upgrading the firmware on the
>>> controller card signficantly increased performance.
>>>
>>> But I think you need to post some further information about the
>>> problem. "IO" can be rooted in a lot of issues. :)
>>>
>>>
>>> Adrian
>>>
>>>
>>
>> --
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>> Sent from the Squid - Users mailing list archive at Nabble.com.
>>
>>
>
>

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