Re: [squid-users] memory utilization

  Hi Amos,

Really your support is grateful to us.You always help us to
understanding of squid and its work pattern.Thanks for your kind support.

> On 21/11/2011 1:33 a.m., benjamin fernandis wrote:
>> Hi All,
>>
>> I configured squid box to get good cache performance and for that i
>> set cache_mem and object size in cache.
>>
>> cat /etc/squid/squid.conf | grep cache_mem
>> cache_mem 6144 MB
>>
>> cat /etc/squid/squid.conf | grep -i maximum_object_size_in_memory
>> maximum_object_size_in_memory 1 MB
>>
>> And whenever i check memory usage at OS level while squid is serving
>> to traffic. it shows me
>>
>> free -mto
>> total used free shared buffers
>> cached
>> Mem: 7995 345 7650 0
>> 30 78
>> Swap: 8999 0 8999
>> Total: 16995 345 16650
>>
>>
>> So as per my squid setup i set 6GB , So why free -mto showing me that
>> only 345 mb is used and 7650 mb is free.
>>
>>
>> As per my understanding , if i assign 6GB RAM to squid then 6GB will
>> be deducted from my actual memory and then OS has that remaining
>> amount of memory.
>>
>> My perception is right ?
>
> Yes your understanding is generally correct.
>
> There is one circumstance I can think of when the OS might show lower
> than cache_mem usage. That is when memory pooling control has been
> disabled when building Squid. In that case Squid will not pre-allocate
> any memory for use.
>

If suppose memory pooling control has been disabled in that case, does
squid will not have full control on memory utilization or suppose i
assign 6 GB ram to squid, so does squid use 6gb ram for caching ?

Memory pooling control is mandatory to enable in squid while we are
talking for memory utilization or work flow of squid ?

>>
>>
>> What is the purpose of --enable-async-io option in squid?
>
> To enable Asynchrnous I/O (AIO) for threaded read/write to disks. This
> is required for AUFS.
>
Yes, i am using AUFS.
>> i read on internet that it enable more performance while using more
>> thread with that option
>
> Yes. Up to the amount of AIO threads your disk controller can work
> with efficiently. There is a point at which the threads become too
> many for the controller and things get slow again. I'm not personally
> aware what that upper limit is.
>
i installed squid rpm which i got from my os distro.i used fedora 15 64
bit.But i can't find that option in squid -v command.so i guess that is
not included while installing squid from rpm.

So --enable-async-io is mandatory while we r using AUFS or while we are
talking for performance how many thread is idle for squid. On internet i
see 128 thread configuration at many blogs.

Suppose --enable-async-io is not enabled with squid so in that case what
is default thread for AUFS?

>> is it correct information which i have ?
>>
>> My squid version is Squid Cache: Version 3.1.15
>>
>> i used squid rpm which i have from my fedora 15 64 bit os in that i
>> can't have that option is enabled
>>
>> so this option is really useful for better performance in high
>> network traffic ?
>
> See above. Only if you are disk caching using AUFS.
>
> Amos

Warm Regards,
Benjamin
Received on Mon Nov 21 2011 - 05:05:36 MST