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<div>I have attached strace to Squid and waited until the download rate has decreased to 500 KB/sec.<br/>
</div>
<div>I used "cache_dir aufs /var/cache/squid3 88894 16 256 max-size=10737418240".</div>
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<div> </div>
<div>Here is the download link:</div>
<div>http://w1.wikisend.com/node-fs/download/6a004a416f65b4cdf7f8eff4ff961199/squid.strace</div>
<div> </div>
<div>I hope it can help you.</div>
<div> </div>
<div name="quote" style="margin:10px 5px 5px 10px; padding: 10px 0 10px 10px; border-left:2px solid #C3D9E5; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">
<div style="margin:0 0 10px 0;"><b>Gesendet:</b> Donnerstag, 23. Juli 2015 um 13:29 Uhr<br/>
<b>Von:</b> "Marcus Kool" <marcus.kool@urlfilterdb.com><br/>
<b>An:</b> "Jens Offenbach" <wolle5050@gmx.de>, "Eliezer Croitoru" <eliezer@ngtech.co.il>, "Amos Jeffries" <squid3@treenet.co.nz>, squid-users@lists.squid-cache.org<br/>
<b>Betreff:</b> Re: [squid-users] Squid3: 100 % CPU load during object caching</div>
<div name="quoted-content">I am not sure if it is relevant, maybe it is:<br/>
<br/>
I am developing an ICAP daemon and after the ICAP server sends a "100 continue"<br/>
Squid sends the object to the ICAP server in small chunks of varying sizes:<br/>
4095, 5813, 1448, 4344, 1448, 1448, 2896, etc.<br/>
Note that the interval of receiving the chunks is 1/1000th of a second.<br/>
It seems that Squid forwards the object to the ICAP server every time it receives<br/>
one or a few TCP packets.<br/>
<br/>
I have a suspicion that in the scenario of 100% CPU, large #write calls and low throughput a similar thing is happening:<br/>
Squid physically stores a small part of the object many times, i.e. every time one or a few TCP packets arrive.<br/>
<br/>
Amos, is there a debug setting that can confirm/reject this suspicion?<br/>
<br/>
Marcus<br/>
<br/>
<br/>
On 07/23/2015 04:25 AM, Jens Offenbach wrote:<br/>
> A test with ROCK "cache_dir rock /var/cache/squid3 51200" gives very confusing results.<br/>
><br/>
> I cleared the cache:<br/>
> rm -rf /var/cache/squid3/*<br/>
> squid -z<br/>
> squid<br/>
> http_proxy=<a href="http://139.2.57.120:3128/" target="_blank">http://139.2.57.120:3128/</a> wget http://test-server/freesurfer-Linux-centos6_x86_64-stable-pub-v5.3.0.tar<br/>
><br/>
> The download starts with 10 MB/sec and stays constant for 1 minutes, then it drops gradually to 1 MB/sec and stays there for some time. After 5 minutes the download rate returns back to 10 MB/sec very quickly and drops again step-by-step to 1 MB/sec. After 5-6 minutes the download rates rises again to 10 MB/sec and drops again gradually to 1 MB/sec.<br/>
><br/>
> During caching progress, we have 100 % CPU usage and a disk IO that is corresponds with the download rate.<br/>
><br/>
> For further investigations I give you my build properties:<br/>
> squid -v<br/>
> Squid Cache: Version 3.5.6<br/>
> Service Name: squid<br/>
> configure options: '--build=x86_64-linux-gnu' '--prefix=/usr' '--includedir=/include' '--mandir=/share/man' '--infodir=/share/info' '--sysconfdir=/etc' '--localstatedir=/var' '--libexecdir=/lib/squid3' '--srcdir=.' '--disable-maintainer-mode' '--disable-dependency-tracking' '--disable-silent-rules' '--datadir=/usr/share/squid3' '--sysconfdir=/etc/squid3' '--mandir=/usr/share/man' '--enable-inline' '--enable-async-io=8' '--enable-storeio=ufs,aufs,diskd,rock' '--enable-removal-policies=lru,heap' '--enable-delay-pools' '--enable-cache-digests' '--enable-underscores' '--enable-icap-client' '--enable-follow-x-forwarded-for' '--enable-auth-basic=DB,fake,getpwnam,LDAP,NCSA,NIS,PAM,POP3,RADIUS,SASL,SMB' '--enable-auth-digest=file,LDAP' '--enable-auth-negotiate=kerberos,wrapper' '--enable-auth-ntlm=fake,smb_lm' '--enable-external-acl-helpers=file_userip,kerberos_ldap_group,LDAP_group,session,SQL_session,unix_group,wbinfo_group' '--enable-url-rewrite-helpers=fake' '--enable-eui' '--enable-e<br/>
s<br/>
i' '--enable-icmp' '--enable-zph-qos' '--enable-ecap' '--disable-translation' '--with-swapdir=/var/cache/squid3' '--with-logdir=/var/log/squid3' '--with-pidfile=/var/run/squid3.pid' '--with-filedescriptors=65536' '--with-large-files' '--with-default-user=proxy' '--enable-linux-netfilter' 'build_alias=x86_64-linux-gnu' 'CFLAGS=-g -O2 -fPIE -fstack-protector --param=ssp-buffer-size=4 -Wformat -Werror=format-security -Wall' 'LDFLAGS=-Wl,-Bsymbolic-functions -fPIE -pie -Wl,-z,relro -Wl,-z,now' 'CPPFLAGS=-D_FORTIFY_SOURCE=2' 'CXXFLAGS=-g -O2 -fPIE -fstack-protector --param=ssp-buffer-size=4 -Wformat -Werror=format-security'<br/>
><br/>
><br/>
> Gesendet: Mittwoch, 22. Juli 2015 um 21:47 Uhr<br/>
> Von: "Eliezer Croitoru" <eliezer@ngtech.co.il><br/>
> An: squid-users@lists.squid-cache.org<br/>
> Betreff: Re: [squid-users] Squid3: 100 % CPU load during object caching<br/>
> On 22/07/2015 21:59, Eliezer Croitoru wrote:<br/>
>> Hey Jens,<br/>
>><br/>
>> I have tested the issue with LARGE ROCK and not AUFS or UFS.<br/>
>> Using squid or not my connection to the server is about 2.5 MBps (20Mbps).<br/>
>> Squid is sitting on an intel atom with SSD drive and on a HIT case the<br/>
>> download speed is more then doubled to 4.5 MBps(36Mbps).<br/>
>> I have not tried it with AUFS yet.<br/>
><br/>
><br/>
> And I must admit that AUFS beats rock cache with speed.<br/>
> I have tried rock with basic "cache_dir rock /var/spool/squid 8000" vs<br/>
> "cache_dir aufs /var/spool/squid 8000 16 256" and the aufs cache HIT<br/>
> results more then doubles 3 the speed rock gave with default settings.<br/>
><br/>
> So about 15MBps which is 120Mbps.<br/>
> I do not seem to feel what Jens feels but the 100% CPU might be because<br/>
> of spinning disk hangs while reading the file from disk.<br/>
><br/>
> Amos, I remember that there were some suggestions how to tune large rock.<br/>
> Any hints?<br/>
> I can test it and make it a suggestion for big files.<br/>
><br/>
> Eliezer<br/>
><br/>
> _______________________________________________<br/>
> squid-users mailing list<br/>
> squid-users@lists.squid-cache.org<br/>
> <a href="http://lists.squid-cache.org/listinfo/squid-users" target="_blank">http://lists.squid-cache.org/listinfo/squid-users</a><br/>
> _______________________________________________<br/>
> squid-users mailing list<br/>
> squid-users@lists.squid-cache.org<br/>
> <a href="http://lists.squid-cache.org/listinfo/squid-users" target="_blank">http://lists.squid-cache.org/listinfo/squid-users</a><br/>
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