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From "Mathihalli, Madhusudan" <mad...@hp.com>
Subject RE: mod_cache performance
Date Tue, 03 Aug 2004 17:11:05 GMT


: -----Original Message-----
: From: Bill Stoddard [mailto:bill@wstoddard.com] 
[SNIP]
: > 
: > Here's some comparative numbers to chew on.
: > 
: > One client and one server on 100Mbps network (cheapy 
: 100Base-T switch);
: > 50 simulated users hitting 7 URLs 100 times with flood 
: (35,000 requests).
: > 
: > mod_disk_cache: Requests: 35000 Time: 40.91 Req/Sec: 856.78
: > mod_mem_cache:  Requests: 35000 Time: 54.90 Req/Sec: 637.81
: > no cache:       Requests: 35000 Time: 54.86 Req/Sec: 638.81
: > squid:          Requests: 35000 Time: 105.35 Req/Sec: 332.25
: > 
: > mod_disk_cache completely filled out the network at ~50% CPU usage.
: >    [Can't push through more than ~8MB/sec (~64Mb/sec) without GigE.]
: > mod_mem_cache filled up the CPU but not the network
: >    [Poor scaling characteristics.  It goes to 100% CPU with 
: just 5 users!]
: 
: mod_mem_cache is broken then. It used to kick the pants off 
: of 'no cache' and mod_disk_cache.

.. Well, doesn't it depend upon the size of the data set. With 'ab', I
guess that's possible that mod_mem_cache can beat mod_disk_cache - but
with a dataset like SPECweb99, I'd really doubt if it can really do it.

BTW, I wonder how mem_cache can significantly out-perform no-cache
scenario - 'cause a good file system should buffer cache the
most-accessed files, and there should be minimal perf. difference.

-Madhu

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