Re: [squid-users] Big IO load.. with only few files.. how come? from Torsten.Lange@dont-contact.us on 2001-11-12 (squid-users)

From: <[email protected]>
Date: Mon, 12 Nov 2001 17:43:19 +0100

i see your point:

Internal Data Structures:
            42807 StoreEntries
---> 261 StoreEntries with MemObjects
              160 Hot Object Cache Items
            42709 on-disk objects

to me it appears that squid prefers writing objects into it's cache
directories
instead of putting them into the cache_mem.

have you tried playing with the 'maximum_object_size_in_memory' value?

alternatively, you can try defining your cache_dirs as cache_dir type
'null'.
this should keep squid from using your disks for testing purposes.

and maybe a raid array is not really the fastest access mechanism you
can get for squid - even if it is a hardware-based raid array.

Best regards

Torsten Lange

---------------------- Forwarded by Torsten Lange/Kerpen/GECITS-EU on
12.11.2001 17:37 ---------------------------

ktk@metropol.dk on 12.11.2001 17:34:59

To: Torsten.Lange@GECITS-EU.COM
cc: squid-users@squid-cache.org
Subject: Vedr.: Re: [squid-users] Big IO load.. with only few files.. how
        come?


--------------------------------------------------------------------------

I see what you mean..

But that doesn't quite explain why the Memory usage for squid via mallinfo
():
is Total space in arena: 13224 KB (see more below)..

the only reason it seemed to stop serving, was because of the IO load...
the disk-io load that is..
as the ram is much faster, I'm of course saddened by the fact, that It
doesn't keep all the objects it can in the memory..

I've set it to use 800MB for memory-objects.. yet it only uses 13MB - 261
objects out approx. 42.000 objects in memory..
that makes me a bit sad..

can you tell me why it doesn't keep as many objects as possible in the
memory?

P.S. the machine, is a 2x PIII-1ghz - with an IBM 4L - 160mb/s raid1 - and
10k rpm disks.. running Linux 2.4 and reiserfs on the cache_dir. it could
probably serve more IO if I had the raidctrl. with a bigger cache..
but I've never seen this big an IO load.. not even when serving files with
apache - with similar loads.. (apache slows down to a crawl though - which
is our reason for shifting to squid)..

-------------| This mail has been sent to you by: |------------
Klavs Klavsen, IT-coordinator and Systems Administrator at
Metropol Online - http://www.metropol.dk
Tlf. 33752700, Fax 33752720, Email ktk@metropol.dk

Private- Email [email protected] - http://www.vsen.dk

--------------------[ I believe that... ]-----------------------
It is a myth that people resist change. People resist what other
people make them do, not what they themselves choose to do...
That's why companies that innovate successfully year after year
seek their peopl's ideas, let them initiate new projects and
encourage more experiments. -- Rosabeth Moss Kanter

hmm...

<HTTP requests per minute: 55174.3>
that means an average of 919,57 requests per second.

i think this is a bit too optimistic for stress-testing squid :o).
that must be a hellraising machine, then...

now seriously, i never heard of any <normal> squid box
that could stand >900 requests per second.

you can find some measurements (IRCache cache-off)
at:

http://www.measurement-factory.com/results/public/cacheoff/N03/report.by-meas.html

i never got squid running stable on a 1gb/p3-866 machine
with more than 400 req/second.

Torsten

--------------------------------------------------------------------------

Hi guys,

squid still has a lot of users right now.. the IO is tremendous.. very
high..

Even though it's very select group of files that are accessed.. this is
very weird as the box has 1gb of ram,
and should be able to keep the entire set of files accessed in ram.. the
AIO processes I have set for max of 350 procs..
it now again hits a queue congestion - seemingly because of the disk-io not
keeping up..

why is squid not keeping the objects in the memory? :-(
|---------+-----------------------|
| Start | Mon, 12 Nov 2001 |
| Time: | 15:55:29 GMT |
|---------+-----------------------|
| Current | Mon, 12 Nov 2001 |
| Time: | 15:59:32 GMT |
|---------+-----------------------|

Connection information for squid:
           Number of clients accessing cache: 745
           Number of HTTP requests received: 224313
           Number of ICP messages received: 0
           Number of ICP messages sent: 0
           Number of queued ICP replies: 0
           Request failure ratio: 0.00%
           HTTP requests per minute: 55174.3
           ICP messages per minute: 0.0
           Select loop called: 33758 times, 7.226 ms avg
Cache information for squid:
           Request Hit Ratios: 5min: 1.6%, 60min: 1.6%
           Byte Hit Ratios: 5min: 24.1%, 60min: 24.1%
           Request Memory Hit Ratios: 5min: 7.4%, 60min: 7.4%
           Request Disk Hit Ratios: 5min: 38.2%, 60min: 38.2%
           Storage Swap size: 934476 KB
           Storage Mem size: 3040 KB
           Mean Object Size: 21.88 KB
           Requests given to unlinkd: 0
Median Service Times (seconds) 5 min 60 min:
           HTTP Requests (All): 0.04776 0.04776
           Cache Misses: 0.05046 0.05046
           Cache Hits: 0.02069 0.02069
           Near Hits: 0.07014 0.07014
           Not-Modified Replies: 0.02190 0.02190
           DNS Lookups: 0.31806 0.31806
           ICP Queries: 0.00000 0.00000
Resource usage for squid:
           UP Time: 243.932 seconds
           CPU Time: 244.930 seconds
           CPU Usage: 100.41%
           CPU Usage, 5 minute avg: 100.40%
           CPU Usage, 60 minute avg: 100.40%
           Maximum Resident Size: 0 KB
           Page faults with physical i/o: 358
Memory usage for squid via mallinfo():
           Total space in arena: 13224 KB
           Ordinary blocks: 13184 KB 1674 blks
           Small blocks: 0 KB 0 blks
           Holding blocks: 404 KB 2 blks
           Free Small blocks: 0 KB
           Free Ordinary blocks: 39 KB
           Total in use: 13588 KB 103%
           Total free: 39 KB 0%
Memory accounted for:
           Total accounted: -1 KB
           memPoolAlloc calls: 29572746
           memPoolFree calls: 29478662
File descriptor usage for squid:
           Maximum number of file descriptors: 1024
           Largest file desc currently in use: 412
           Number of file desc currently in use: 367
           Files queued for open: 1
           Available number of file descriptors: 656
           Reserved number of file descriptors: 100
           Store Disk files open: -70
Internal Data Structures:
            42807 StoreEntries
              261 StoreEntries with MemObjects
              160 Hot Object Cache Items
            42709 on-disk objects

[root]# vmstat 1 100
procs memory swap io system
cpu
r b w swpd free buff cache si so bi bo in cs us sy
id
1 0 1 4344 241360 73008 581044 0 0 0 0 18347 218 35
23 41
1 0 1 4344 241368 73008 581036 0 0 0 0 18384 225 31
29 40
1 0 1 4344 241340 73008 581052 0 0 0 812 18344 255 30
28 41
1 0 1 4344 241256 73008 581052 0 0 0 0 18152 347 30
27 43
0 0 1 4344 241180 73008 581084 0 0 16 0 18222 245 38
20 43
1 0 0 4344 241044 73008 581084 0 0 0 0 18212 232 38
20 42
1 0 1 4344 241040 73008 581088 0 0 0 0 18245 368 30
27 43
1 0 1 4344 241040 73008 581088 0 0 0 588 18232 282 34
25 41
1 0 0 4344 241028 73008 581088 0 0 0 0 18134 398 37
24 40
1 0 1 4344 241020 73008 581096 0 0 0 0 18322 327 33
25 42
1 0 1 4344 240972 73008 581108 0 0 0 0 18465 306 38
20 42
2 0 1 4344 240972 73008 581108 0 0 0 0 18028 400 32
26 41
1 0 1 4344 240972 73008 581108 0 0 0 780 18207 342 34
24 42
2 0 1 4344 240968 73008 581112 0 0 0 0 18000 428 37
21 42
1 0 1 4344 240960 73008 581120 0 0 0 0 18059 335 40
20 40
1 0 1 4344 240908 73008 581132 0 0 0 0 18016 388 33
27 40
1 0 1 4344 240888 73008 581136 0 0 0 0 18250 407 36
22 42
5 0 0 4344 240852 73008 581136 0 0 0 740 18119 397 39
21 40
1 0 1 4344 240844 73008 581136 0 0 0 0 18253 199 40
17 43
1 0 0 4344 240840 73008 581136 0 0 0 0 18227 251 33
25 42
1 0 1 4344 240848 73008 581136 0 0 0 0 18177 239 31
29 40
1 0 1 4344 240848 73008 581136 0 0 0 0 18388 181 30
29 41
1 0 1 4344 240848 73008 581136 0 0 0 224 18418 245 35
28 38
0 0 1 4344 240844 73008 581140 0 0 0 0 18467 199 35
22 42
1 0 1 4344 240772 73008 581172 0 0 16 0 18367 320 38
21 41
1 0 1 4344 240704 73008 581188 0 0 0 0 18411 283 35
21 43
1 0 1 4344 240704 73008 581188 0 0 0 0 18438 247 32
27 41
1 0 1 4344 240700 73008 581188 0 0 0 592 18438 363 38
20 41
1 0 1 4344 240700 73008 581188 0 0 0 0 18139 422 37
21 42
1 0 1 4344 240696 73008 581188 0 0 0 0 18265 325 35
23 41

Private- Email [email protected] - http://www.vsen.dk

This archive was generated by hypermail pre-2.1.9 : Tue Dec 09 2003 - 17:04:03 MST