Re: Performance tuning

Christopher Stein wrote:

> - What should I set cache_mem to? How does one
> decide on this value?

It depends on your OS and workload. It should at least be 2 MB + 15
seconds of traffic. More if your OS have slow or inefficient (for Squid)
disk buffer management.

> - the number of SwapDirs?,

One per physical drive.

> - number of L1 and L2 directories for on-disk cache?

L2 = 256
L1 at least cache_dir_size * 2 / store_avg_object_size / L2 / L2 + 1

> - the low-water and high-water marks for both the
> cache-mem and the on-disk cache?

cache_mem does not have a low water mark.

for cache_swap_[low|high], set them somewhat closer than the default.

> - the average size of a cached object (used by Squid to
> size the SwapDir's FileMap)?

You should be able to leave this at the default, or set it to a somewhat
lower value. Do NOT set it to a higher value. A good approach is perhaps
to begin with the default value, and when your cache is filled to 50%,
use cachemgr to find out your real average object size, and if lower
reconfigure Squid.

Also remember to tune the delay pools settings, or Squid could use a lot
of memory for nothing.

delay_pools_limit 32 MB (or less)
or
delay_pools off

depending on what malloc library you are using.

--
Henrik Nordstrom
Squid hacker