Re: [squid-users] squid cpu problem

This looks like the CPU cycles are being consumed by walking one or more
very long lists of memory pieces and writing them to disk one by one.
Note the UFSStoreState::write parameter size=4096 in the backtrace for
how bit those memory pages are.

Which could happen if you cached a very big object in cache_mem and then
a random time later it needed swapping out to disk to free up memory.

It could also happen if Squid needed to suddenly swap out a large number
of smaller items to make memory space available for a large one which is
about to arrive.

So, have you configured Squid to allow very large objects (many MB or
GB) in memory storage?

Note these causes would not show up in the testing you mentioned unless
you had a very wide range of test object sizes being pumped randomly
through the proxy. A tool like web polygraph is best to test that
traffic behaviour accurately.

Amos

On 5/04/2014 1:59 a.m., a.afach wrote:
> Dear all
> i still have the CPU spikes even when i used
> disable-strict-error-checking without using Cflags
>
> this is the gdb backtrace while the CPU spikes
>
> 0x000000000051b348 in linklistPush (L=0x11853e188, p=0xce6d4300) at
> list.cc:47
> 47 while (*L)
> (gdb) backtrace
> #0 0x000000000051b348 in linklistPush (L=0x11853e188, p=0xce6d4300) at
> list.cc:47
> #1 0x00000000005a70a1 in UFSStoreState::write (this=0xb3970e28,
> buf=0x11fe69ca0
> "!v\253r[/\307\232G\b\375`\237:\213\256^\335\373{\241%\232\363\021\071>`\342\033\177a\202G\320{\323%\236K\342\243*\332\316\351\231=\360\370\313Ro=\317\262\243\315\027\351,\221\230\353Z\023\024q\"QSC\036\214:M\242{@\351m\020\337Cw_\214\216\304\226\265\a\375\031\211\243V\222T\320\016\227\312-\211Sz\326^\346\230\251\327\222\n\373I\032\341\303==U\214\277\264\244\205\b1\346S=\230\215\204\245\254>\312\223\066\336\230PpP\227\271\370\266;\362\226\242\036\225\235w\330\325\061\316{o_\364\021\062\351\376\062|\313\006`\357m\206FQ0\021\030C\224\004]\336\315\371\033h1\361\363\350d\366\066"...,
> size=4096, aOffset=-1, free_func=0x5203b0 <memNodeWriteComplete(void*)>)
> at ufs/store_io_ufs.cc:247
> #2 0x0000000000554ca0 in doPages (anEntry=<optimized out>) at
> store_swapout.cc:160
> #3 StoreEntry::swapOut (this=0x372ca10) at store_swapout.cc:279
> #4 0x000000000054c986 in StoreEntry::invokeHandlers (this=0x372ca10) at
> store_client.cc:714
> #5 0x00000000004dc1a7 in FwdState::complete (this=0xbb502b48) at
> forward.cc:341
> #6 0x00000000005579a5 in ServerStateData::completeForwarding
> (this=0xf8030588) at Server.cc:239
> #7 0x00000000005571bd in ServerStateData::serverComplete2
> (this=0xf8030588) at Server.cc:207
> #8 0x00000000004ff3dc in HttpStateData::processReplyBody
> (this=0xf8030588) at http.cc:1382
> #9 0x00000000004fd367 in HttpStateData::readReply (this=0xf8030588,
> io=...) at http.cc:1161
> #10 0x0000000000503156 in JobDialer<HttpStateData>::dial
> (this=0xde75ca50, call=...) at base/AsyncJobCalls.h:175
> #11 0x0000000000569ee4 in AsyncCall::make (this=0xde75ca20) at
> AsyncCall.cc:34
> #12 0x000000000056cb76 in AsyncCallQueue::fireNext (this=<optimized
> out>) at AsyncCallQueue.cc:53
> #13 0x000000000056ccf0 in AsyncCallQueue::fire (this=0x2586400) at
> AsyncCallQueue.cc:39
> #14 0x00000000004d385c in EventLoop::runOnce (this=0x7fffcb3518d0) at
> EventLoop.cc:130
> #15 0x00000000004d3938 in EventLoop::run (this=0x7fffcb3518d0) at
> EventLoop.cc:94
> #16 0x000000000051d35b in SquidMain (argc=<optimized out>,
> argv=<optimized out>) at main.cc:1418
> #17 0x000000000051dd83 in SquidMainSafe (argv=<optimized out>,
> argc=<optimized out>) at main.cc:1176
> #18 main (argc=<optimized out>, argv=<optimized out>) at main.cc:1168
>
>
> any idea about what's causing the cpu spike
>
>
> On 2014-03-31 16:34, Amos Jeffries wrote:
>> On 2014-04-01 02:10, a.afach wrote:
>>> Dear Eliezer
>>> these are the configure options ...
>>> configure options: '--prefix=/usr/local/squid-3.1.19'
>>> '--sysconfdir=/etc' '--sysconfdir=/etc/squid' '--localstatedir=/var'
>>> '--enable-auth=basic,digest,ntlm' '--enable-removal-policies=lru,heap'
>>> '--enable-digest-auth-helpers=password'
>>> '--enable-basic-auth-helpers=PAM,getpwnam,NCSA,MSNT'
>>> '--enable-external-acl-helpers=ip_user,session,unix_group'
>>> '--enable-ntlm-auth-helpers=fakeauth'
>>> '--enable-ident-lookups--enable-useragent-log'
>>> '--enable-cache-digests' '--enable-delay-pools' '--enable-referer-log'
>>> '--enable-arp-acl' '--with-pthreads' '--with-large-files'
>>> '--enable-htcp' '--enable-carp' '--enable-follow-x-forwarded-for'
>>> '--enable-snmp' '--enable-ssl' '--enable-storeio=ufs,diskd,aufs'
>>> '--enable-async-io' '--enable-linux-netfilter' '--enable-epoll'
>>> '--with-squid=/usr/squid-3.1.19' '--disable-ipv6' '--with-aio'
>>> '--with-aio-threads=128' 'build_alias=x86_64-pc-linux-gnu'
>>> 'host_alias=x86_64-pc-linux-gnu' 'CC=x86_64-pc-linux-gnu-gcc'
>>> 'CFLAGS=-O2 -pipe -m64 -mtune=generic' 'LDFLAGS=-Wl,-O1
>>> -Wl,--as-needed' 'CXXFLAGS=' '--cache-file=/dev/null' '--srcdir=.'
>>>
>>
>> Some more reasons to upgrade:
>> * --disable-strict-error-checking avoids issues on Gentoo with -Werror
>> * CFLAGS affects the C compiler, not the C++ compiler. C compiler is
>> only used by Squid-3 to build some libraries.
>> * current verified stable Gentoo Squid version is 3.3.8.
>> * updating aything on Gentoo involves rebuilding a surprising number
>> of components from scratch. So when you get a difference like this it
>> really could be anywhere. Including buried in the compiler itself -
>> your flags are possibly changing optimization levels and CPU-specific
>> assembly instructions used by it.
>>
>> Amos
Received on Sat Apr 05 2014 - 08:37:15 MDT