Re: [squid-users] squid performance tunning

From: Drunkard Zhang <>
Date: Thu, 18 Aug 2011 18:11:54 +0800

2011/8/18 Amos Jeffries <>:
> On 18/08/11 19:40, Drunkard Zhang wrote:
>> 2011/8/18 Chen Bangzhong:
>>> My cached objects will expire after 10 minutes.
>>> Cache-Control:max-age=600
>> Static content like pictures should cache longer, like 1 day, 86400.
> Could also be a whole year. If you control the origin website, set caching
> times as large as reasonably possible for each object. With revalidate
> settings relevant to its likely replacement needs. And always send a correct
> ETag.
> With those details Squid and other caches will take care of reducing caching
> times to suit the network and disk needs and updates/revalidation to suit
> your needs. So please set it large.
>>> I don't know why there are so many disk writes and there are so many
>>> objects on disk.
> All traffic goes through either RAM cache or if its bigger than
> maximum_object_size_in_memory will go through disks.
> From that info report ~60% of your traffic bytes are MISS responses. A large
> portion of that MISS traffic is likely not storable, so will be written to
> cache then discarded immediately. Squid is overall mostly-write with its
> disk behaviour.
> Likely your 10-minute age is affecting this in a big way. The cache will
> have a lot of storable object which are stale. Next request they will be
> fetched into memory, then replaced by a revalidation REFRESH (near-HIT)
> response, which writes new data back to disk later.
>>> In addtion, Disk hits as % of hit requests: 5min: 1.6%, 60min: 1.9%
>>> is very low.
>> Maybe cause by disk read timeout. You used too much disk space, you
>> can shrink it a little by a little, until disk busy percentage reduced
>> to 80% or lower.
> Your Squid version is one which will promote HIT objects from disk and
> service repeat HITs from memory. Which reducing that disk-hit % a lot more
> than earlier squid versions would show it as.
>>> Can I increase the cache_mem´╝č or not use disk cache at all?
>> I used all memory I can use :-)
> Indeed, the more the merrier. Unless it is swapping under high load. If that
> happens Squid speed goes terrible almost immediately.

Actually I disabled swap at all, and use a script to start squid
process immediately when killed by OS. OS will kill squid when OOM(Out
of memory).
Received on Thu Aug 18 2011 - 10:12:20 MDT

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