have been testing the cache running strictly off memory and no disk fs.
When Squid is set to use 16gb memory, connections are very fast.
When I bumped the memory use to anything near 30 gb, latency becomes an
issue.
The cache doesn't report any errors in cache.log and watching the
access.log I don't see anything
out of the ordinary.
I never have seen the cachemgr report any "Store Disk file open" values.
Again, this is a dedicated squid server with 32gb ram and 4 dedicated
280+gb 15k sata drives
running transparently using wccp.
Presently the 4 drives are partitioned in 1/2, allocated to squid0-squid7.
Any recommendations on repartitioning the 4 drives for quicker reads?
here's a general runtime report fwiw:
Squid Object Cache: Version 2.7.STABLE4-20080926
Start Time: Tue, 07 Oct 2008 18:21:10 GMT
Current Time: Wed, 15 Oct 2008 15:51:20 GMT
Connection information for squid:
Number of clients accessing cache: 5393
Number of HTTP requests received: 220293340
Number of ICP messages received: 0
Number of ICP messages sent: 0
Number of queued ICP replies: 0
Request failure ratio: 0.00
Average HTTP requests per minute since start: 19374.7
Average ICP messages per minute since start: 0.0
Select loop called: -454862289 times, -1.500 ms avg
Cache information for squid:
Request Hit Ratios: 5min: 32.8%, 60min: 32.3%
Byte Hit Ratios: 5min: 14.1%, 60min: 15.9%
Request Memory Hit Ratios: 5min: 56.9%, 60min: 56.5%
Request Disk Hit Ratios: 5min: 0.1%, 60min: 0.1%
Storage Swap size: 0 KB
Storage Mem size: 16777692 KB
Mean Object Size: 0.00 KB
Requests given to unlinkd: 0
Median Service Times (seconds) 5 min 60 min:
HTTP Requests (All): 0.06640 0.06286
Cache Misses: 0.10281 0.09736
Cache Hits: 0.00000 0.00000
Near Hits: 0.05046 0.05046
Not-Modified Replies: 0.00000 0.00000
DNS Lookups: 0.04854 0.02941
ICP Queries: 0.00000 0.00000
Resource usage for squid:
UP Time: 682209.558 seconds
CPU Time: 133086.580 seconds
CPU Usage: 19.51%
CPU Usage, 5 minute avg: 15.85%
CPU Usage, 60 minute avg: 15.31%
Process Data Segment Size via sbrk(): 18876028 KB
Maximum Resident Size: 0 KB
Page faults with physical i/o: 4381750
Memory usage for squid via mallinfo():
Total space in arena: -2095492 KB
Ordinary blocks: 2096010 KB 22166 blks
Small blocks: 0 KB 0 blks
Holding blocks: 67624 KB 12 blks
Free Small blocks: 0 KB
Free Ordinary blocks: 2801 KB
Total in use: -2030670 KB 100%
Total free: 2801 KB 0%
Total size: -2027868 KB
Memory accounted for:
Total accounted: 18253692 KB
memPoolAlloc calls: 4284254700
memPoolFree calls: 4256906586
File descriptor usage for squid:
Maximum number of file descriptors: 32000
Largest file desc currently in use: 8829
Number of file desc currently in use: 5500
Files queued for open: 0
Available number of file descriptors: 26500
Reserved number of file descriptors: 100
Store Disk files open: 0
IO loop method: epoll
Internal Data Structures:
932205 StoreEntries
932205 StoreEntries with MemObjects
931937 Hot Object Cache Items
0 on-disk objects
thanks
-Ryan
Ryan Thoryk wrote:
The latency should be your disk caches, and I'm also assuming that the
sheer size of them could be contributing to it. Also remember that
RAID-0 (or similar) won't help improve performance (since it's access
times that you need, not throughput). We have a much smaller load here
(one machine peaks at around 1100 users), and switching from 7200rpm
SATA drives to 15k SCSI drives solved a lot of latency issues.
One thing you can do is use the max_open_disk_fds value; we found that
our SATA machines had major performance issues when over 50 file
descriptors were currently open. That parameter tells Squid to bypass
the disk cache if the number of open fd's is over that value (that would
definitely help during peak times). You can find the current number of
open fd's in the "Store Disk file open" value in your cachemgr general
runtime page.
Also I'd recommend greatly decreasing the size of your disk caches, and
increasing the cache_mem value (since you have 32 gigs of RAM, I'd
probably try to get the Squid process up to around 30 gigs).
Ryan Thoryk
Ryan Goddard wrote:
Thanks for the response, Adrian.
Is recompile required to change to internal DNS?
I've disabled ECN, pmtu_disc and mtu_probing.
cache_dir is as follows:
(recommended by Henrik)
cache_dir aufs /squid0 125000 128 256 cache_dir aufs /squid1 125000
128 256
cache_dir aufs /squid2 125000 128 256
cache_dir aufs /squid3 125000 128 256
cache_dir aufs /squid4 125000 128 256
cache_dir aufs /squid5 125000 128 256
cache_dir aufs /squid6 125000 128 256
cache_dir aufs /squid7 125000 128 256
No peak data available, here's some pre-peak data:
Cache Manager menu
5-MINUTE AVERAGE
sample_start_time = 1222199580.85434 (Tue, 23 Sep 2008 19:53:00 GMT)
sample_end_time = 1222199905.507274 (Tue, 23 Sep 2008 19:58:25 GMT)
client_http.requests = 268.239526/sec
client_http.hits = 111.741117/sec
client_http.errors = 0.000000/sec
IOSTAT shows lots of idle time - I'm unclear what you mean by
"profiling" ?
Also, have not tried running w/out any cache - can you explain
how this is done?
appreciate the assistance.
-Ryan
