I can definitely help here as I have squid setup for a large Educational
setting as well.
I agree with Mr. Crockett's suggestion with regards to hyperthreading.
You will get more use out of all your CPU cache than half of it. Also,
squid would not benefit from the lowered overhead of thread switching
provided by hyperthreading. However I don't think that should affect
what you are seeing.
I'd be concerned with the "Median Service Times / HTTP Requests (All)"
#s that you are seeing. Also, the "Largest file desc currently in use"
of 11111 seems excessively high. I'd guess that your connection is slow
enough that squid is having to hold and back-log too many requests. You
might do well to ssh into your squid box and try doing browsing actually
at the proxy itself and compare the experience with an inside browser
getting the same page through squid. My guess is it is probably the
same--not very fast.
Another thing that might be driving up the # of file desc usage is the
"half_closed_clients off" you have. On my squids I run with this as in
the default config, "on".
Also, on my systems we are running named instead of using squid's fqdn
cache, this may help things out a bit--ymmv..
I was running a squid box with only 1 GB of RAM recently and moved it to
4GB RAM. The only thing I altered was I changed from "cache_mem 128 MB"
to "cache_mem 1024 MB" and "maximum_object_size 256 MB" to
"maximum_object_size 512 MB". I also increased the amount of
"cache_dir" but found that this caused squid to eat up too much RAM for
the disk index and pushed it back to the original setting.
I notice you have a "redirect_children 30"--are you running a
redirector? This can significantly alter your numbers.
We currently have 3 seperate ICP-ing squids and each box has from 3-5
cache drives. If you do not have multiple squids, you might want to
consider more hardware.. Take a look at my CPU usage--these boxes are
kept VERY busy, and I have three of them!
I'll give you my settings. Again I am very conservative on the
"cache_dir" size as I think this will eat up quite a bit of RAM to keep
in-memory-indices.
Most of my squid.conf:
# Timeouts:
read_timeout 5 minutes
request_timeout 30 seconds
pconn_timeout 60 seconds
half_closed_clients on
shutdown_lifetime 0 seconds
negative_ttl 30 seconds
icp_query_timeout 1000 milliseconds
cache_dir aufs /cache1 2048 64 64
cache_dir aufs /cache2 2048 64 64
cache_dir aufs /cache3 2048 64 64
cache_mem 1024 MB
maximum_object_size 512 MB
minimum_object_size 0
request_body_max_size 0
request_header_max_size 64 KB
http_port 3128
cache_store_log none
strip_query_terms off
fqdncache_size 0
coredump_dir /
log_icp_queries off
cachemgr output:
Squid Object Cache: Version 2.5.STABLE4
Start Time: Fri, 27 Feb 2004 21:14:43 GMT
Current Time: Sat, 06 Mar 2004 00:09:24 GMT
Connection information for squid:
Number of clients accessing cache: 7835
Number of HTTP requests received: 22331805
Number of ICP messages received: 17983480
Number of ICP messages sent: 17937548
Number of queued ICP replies: 0
Request failure ratio: 0.00
Average HTTP requests per minute since start: 2177.7
Average ICP messages per minute since start: 3502.9
Select loop called: 186487837 times, 3.299 ms avg
Cache information for squid:
Request Hit Ratios: 5min: 40.7%, 60min: 49.7%
Byte Hit Ratios: 5min: 11.8%, 60min: 13.0%
Request Memory Hit Ratios: 5min: 42.7%, 60min: 24.6%
Request Disk Hit Ratios: 5min: 10.3%, 60min: 9.5%
Storage Swap size: 5662232 KB
Storage Mem size: 1048544 KB
Mean Object Size: 16.77 KB
Requests given to unlinkd: 0
Median Service Times (seconds) 5 min 60 min:
HTTP Requests (All): 0.02742 0.00919
Cache Misses: 0.14252 0.10857
Cache Hits: 0.00179 0.00179
Near Hits: 0.11465 0.08729
Not-Modified Replies: 0.00091 0.00286
DNS Lookups: 0.00372 0.00278
ICP Queries: 0.00249 0.00298
Resource usage for squid:
UP Time: 615280.568 seconds
CPU Time: 217225.410 seconds
CPU Usage: 35.31%
CPU Usage, 5 minute avg: 17.16%
CPU Usage, 60 minute avg: 35.59%
Process Data Segment Size via sbrk(): 1412292 KB
Maximum Resident Size: 0 KB
Page faults with physical i/o: 85601
Memory usage for squid via mallinfo():
Total space in arena: 1412292 KB
Ordinary blocks: 1368846 KB 34984 blks
Small blocks: 0 KB 0 blks
Holding blocks: 21624 KB 7 blks
Free Small blocks: 0 KB
Free Ordinary blocks: 43446 KB
Total in use: 1390470 KB 97%
Total free: 43446 KB 3%
Total size: 1433916 KB
Memory accounted for:
Total accounted: 1274459 KB
memPoolAlloc calls: 2886153831
memPoolFree calls: 2880110606
File descriptor usage for squid:
Maximum number of file descriptors: 4096
Largest file desc currently in use: 946
Number of file desc currently in use: 352
Files queued for open: 1
Available number of file descriptors: 3743
Reserved number of file descriptors: 100
Store Disk files open: 1
Internal Data Structures:
343410 StoreEntries
217719 StoreEntries with MemObjects
217703 Hot Object Cache Items
337566 on-disk objects
HTH,
Peter Smith
James MacLean wrote:
>Hi Folks,
>
>We have tried many suggestions that were found in mail-archives and on
>different sites, but are having a difficult time getting Squid to handle
>our workload. The obvious example of this to me is if we set
>"no_cache deny all", we can start going to sites and notice that they keep
>getting slower.
>
>The Squid server is a 2xP4 Xeon with hyperthreading 2.4Ghz with 1G of RAM.
>They have SCSI drives which we have tried various cache sizes on. There is
>no load on the server before squid begins, but it of course does drive up
>the CPU as it starts to churn.
>
>diskd seems to work the best, but once we start using it, the page load
>delays increase to a point that users are noticing. This setup is used in
>a transparent proxy via the typical Linux redirect.
>
>In this Educational setting we have approx. 12,000 active student/staff if
>I accept the "Largest file desc currently in use:" param, so we realize we
>need some power to deal with the actual disk cache effectiveness. There
>are actually more clients in total, but this seems to give a good guess of
>current activity.
>
>Our Internet feed is a 6Mbs max.
>
>Would like to ask if there are any tuning suggestions we can try to boost
>Squid in this environment?
>
>2.5-STABLE5 cachemgr output follows for a short run :
>
>Connection information for squid:
> Number of clients accessing cache: 799
> Number of HTTP requests received: 261742
> 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: 5769.8
> Average ICP messages per minute since start: 0.0
> Select loop called: 8599 times, 316.530 ms avg
>Cache information for squid:
> Request Hit Ratios: 5min: 17.9%, 60min: 13.7%
> Byte Hit Ratios: 5min: 3.8%, 60min: 1.9%
> Request Memory Hit Ratios: 5min: 25.1%, 60min: 30.8%
> Request Disk Hit Ratios: 5min: 32.0%, 60min: 24.9%
> Storage Swap size: 854948 KB
> Storage Mem size: 128036 KB
> Mean Object Size: 10.22 KB
> Requests given to unlinkd: 0
>Median Service Times (seconds) 5 min 60 min:
> HTTP Requests (All): 2.37608 1.71839
> Cache Misses: 2.79397 1.91442
> Cache Hits: 0.68577 0.61549
> Near Hits: 2.37608 1.91442
> Not-Modified Replies: 0.64968 0.49576
> DNS Lookups: 0.04048 0.03374
> ICP Queries: 0.00000 0.00000
>Resource usage for squid:
> UP Time: 2721.839 seconds
> CPU Time: 506.162 seconds
> CPU Usage: 18.60%
> CPU Usage, 5 minute avg: 78.16%
> CPU Usage, 60 minute avg: 18.46%
> Process Data Segment Size via sbrk(): 219948 KB
> Maximum Resident Size: 0 KB
> Page faults with physical i/o: 0
>Memory usage for squid via mallinfo():
> Total space in arena: 219948 KB
> Ordinary blocks: 219855 KB 375 blks
> Small blocks: 0 KB 0 blks
> Holding blocks: 6788 KB 3 blks
> Free Small blocks: 0 KB
> Free Ordinary blocks: 92 KB
> Total in use: 226643 KB 100%
> Total free: 92 KB 0%
> Total size: 226736 KB
>Memory accounted for:
> Total accounted: 208789 KB
> memPoolAlloc calls: 38921604
> memPoolFree calls: 38222649
>File descriptor usage for squid:
> Maximum number of file descriptors: 32768
> Largest file desc currently in use: 11111
> Number of file desc currently in use: 3641
> Files queued for open: 1
> Available number of file descriptors: 29126
> Reserved number of file descriptors: 100
> Store Disk files open: 46
>Internal Data Structures:
> 88190 StoreEntries
> 17725 StoreEntries with MemObjects
> 17534 Hot Object Cache Items
> 83648 on-disk objects
>
>Lines from sample squid.conf:
>
>request_body_max_size 1000 MB
>httpd_accel_host virtual
>httpd_accel_port 80
>httpd_accel_with_proxy on
>httpd_accel_uses_host_header on
>icp_port 0
>cache_mem 128 MB
>cache_swap_low 90
>cache_swap_high 95
>cache_dir diskd /var/cache/squid/ 2000 64 64
>cache_access_log /var/log/squid/access.log
>cache_log /var/log/squid/cache.log
>cache_store_log /var/log/squid/store.log
>pid_filename /var/run/squid.pid
>debug_options ALL,1
>log_fqdn off
>redirect_children 30
>refresh_pattern ^ftp: 1440 20% 10080
>refresh_pattern ^gopher: 1440 0% 1440
>refresh_pattern . 0 20% 4320
>quick_abort_min 16 KB
>quick_abort_max 16 KB
>quick_abort_pct 95
>forwarded_for off
>minimum_direct_hops 3
>store_avg_object_size 10 KB
>fqdncache_size 16536
>maximum_object_size_in_memory 8 KB
>request_header_max_size 1000 KB
>half_closed_clients off
>
>
>
Received on Fri Mar 05 2004 - 17:15:29 MST
This archive was generated by hypermail pre-2.1.9 : Thu Apr 01 2004 - 12:00:01 MST