[squid-users] Re: Metrics to calculate 'best' values for cache_mem and cache_dir?

From: babajaga <augustus_meyer_at_yahoo.de>
Date: Tue, 27 Mar 2012 12:37:17 -0700 (PDT)

>I've read (for Linux at least) aufs is superior to diskd,<

I have my doubts. First of all, it might depend upon the version of Squid
you want to use.
I use 2.7, and, looking at the source code for aufs, ony reads are async.
Having some discussion with Amos already regarding this issue, he stated,
that async writes were not enabled because being "unstable".
Might be different in other versions, though, but, to be shure, it needs
checking the source code, because it is a conditional compile (ref.:
store_asyncufs.h).

And, in case only reads are async, then it needs further verification,
whether diskd or aufs should be faster.
Because according to my first glance at the code for diskd, diskd does async
writes by default.
Most likely, diskd has more overhead. But, in case of low hit rate for the
cache, I suspects, the performance gains because of async writes might put
diskd into favour.

Actually, I am checking this issue myself for my own stressed squid, running
already in production (LINUX, too).
 
In case, the "writing" considers aufs to be generally faster than diskd, it
looks like, it is ignoring the risk of "unstable" write ops.

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Received on Tue Mar 27 2012 - 19:37:20 MDT

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