Re: Improve TCP_MEM_HITS

Greetings -

--On Friday, June 23, 2000 1:59 pm +0200 Hillel Bilman <hillel@iafrica.com>
wrote:

> How can I improve the TCP_MEM_HITS as with Calamaris these hits
> are only 12.06 % of the entire HITS . The only thing I can see to do
> is to increase the CACHE_MEM amount. Is there any other way to do
> this? Also if your Server is primarily for squid, what % of the total
> RAM available could you safely use for the CACHE_MEM value in the
> squid.conf.

Hah! You think you've got problems at seeing only 12.06% of HITs as
TCP_MEM_HITS?? Take a look at the Calamaris figures from our pair of
caches! ...

WC1:
  status request % kByte % sec kB/sec
  HIT 341954 53.27 1460118 31.40 0 12.08
  TCP_HIT 157029 24.46 988567 21.26 0 33.07
  TCP_IMS_HIT 101250 15.77 47991 1.03 0 31.50
  TCP_REFRESH_HIT 61127 9.52 376929 8.11 1 4.23
  TCP_MEM_HIT 18502 2.88 41550 0.89 0 123.90
  TCP_NEGATIVE_HIT 4046 0.63 5079 0.11 0 99.45

WC2:
  status request % kByte % sec kB/sec
  HIT 263322 42.32 1395711 22.64 0 6.66
  TCP_HIT 140950 22.65 993307 16.11 0 9.91
  TCP_REFRESH_HIT 61574 9.90 329224 5.34 1 3.04
  TCP_IMS_HIT 42811 6.88 30740 0.50 0 36.04
  TCP_MEM_HIT 15804 2.54 39052 0.63 0 159.24
  TCP_NEGATIVE_HIT 2183 0.35 3386 0.05 0 124.26

These are identical (Sun Solaris) systems dedicated to just running Squid.
Each has 640Mb of RAM and 16Gb of local disk for Squid's cache. Average
life-span for items in the cache hovers around 8-and-a-bit days.

To date I've edged Squid's cache_mem setting up to 300Mb on each machine.
This, accordint to "top", leaves Squid running around the 500Mb "SIZE", of
which about 490Mb is "RES"(ident). Although the system has swap space in
use (currently 514Mb in use, with 998Mb free) there is no swapping activity.

I, too, keep wondering how far to edge up the cache_mem setting given these
tpyue of figures. Should it be kept less than real RAM? Or is it OK to go
up further until processes start swapping?

Aside: It's difficult to tell how much memory is left free as Solaris
tends to use it to cache files. For example when I edged up the cache_mem
from 200Mb to 300Mb the free RAM reported by "top" remained at around 20Mb
(but the amount of swap space in use increased somewhat, even though there
is still no active swapping going on).

If anyone can suggest reasonable values, or point towards information about
tuning Squid, I too will be very greatful!

Cheers,

Mike Brudenell

-- 
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