[OpenAFS] Apache and Openafs
Anne Salemme
Anne Salemme <anne@salemme.net>
Thu, 26 Dec 2013 07:36:24 -0800 (PST)
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First thing to check: Is the AFS cache in its own, dedicated filesystem par=
tition.=0A=0ASecond thing to check: When you say you are downloading the sa=
me file multiple times, is it exactly the same file, or is there anything h=
appening to the file so that it =A0changes (ie, some process rewriting the =
file, over and over, etc...even if the contents of the file stay the same)=
=0A=0AThis can be tricky to solve, but I'm sure there's a solution. Good lu=
ck!=0A=0AAnne=0A=0A=0A________________________________=0A From: GALAMBOS Da=
niel <dancsa@dancsa.hu>=0ATo: openafs-info@openafs.org =0ASent: Thursday, D=
ecember 26, 2013 9:48 AM=0ASubject: [OpenAFS] Apache and Openafs=0A =0A=0AH=
i,=0A=0AOur webservice built onto AFS, one node provide the static data, an=
d=0Aworks as a proxy for PHP.=0AOn this server, we have performance problem=
with AFS. This is a Debian=0AWheezy with afs client 1.6.1-3+deb7u1.=0A=0AS=
o we got problems, i cloned the machine and started testing. I used=0Aapach=
e benchmark (ab) against a simple html (w/o pictures or anything,=0Ajust te=
xt). If i downloaded it 2000 times with 50 thread i got high load=0A(18) an=
d ~20 000 context switching in vmstat. The same file with 100=0Athread gene=
rated ~50 load.=0A=0Aafsd is started with the following options:=0AOPTIONS=
=3D"-stat 10000 -dcache 10000 -daemons 6 -volumes 2048 -memcache=0A-chunksi=
ze 18 -rxpck 750 -rxmaxmtu 1500 -prealloc 750"=0A=0Acache size is: 3065648=
=0A=0ADuring the tests no other connection ( except apache status query 1/s=
ec)=0Awas made, the same file was asked for 2000 times.=0A=0AAfter reading =
old messages on this list, i decreased the daemons to 3,=0Awhich caused a v=
ery little improvement.=A0 Reading the apache status i=0Anoticed, that the =
apache spends 4-5 times more time in kernel space than=0Ain users pace.=A0 =
When the same file hosted on the local filesystem the=0Aavg response time d=
ecreased from 1800 ms to 50 ms and there are almost=0Ano load.=0A=0ACould y=
ou help me with this?=0A=0AThanks,=0A=0ADancsa=0A=0A_______________________=
________________________=0AOpenAFS-info mailing list=0AOpenAFS-info@openafs=
.org=0Ahttps://lists.openafs.org/mailman/listinfo/openafs-info
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<html><body><div style=3D"color:#000; background-color:#fff; font-family:ti=
mes new roman, new york, times, serif;font-size:12pt"><div><span>First thin=
g to check: Is the AFS cache in its own, dedicated filesystem partition.</s=
pan></div><div style=3D"background-color: transparent;"><br></div><div styl=
e=3D"background-color: transparent;"><span>Second thing to check: When you =
say you are downloading the same file multiple times, is it exactly the sam=
e file, or is there anything happening to the file so that it changes=
(ie, some process rewriting the file, over and over, etc...even if the con=
tents of the file stay the same)</span></div><div style=3D"background-color=
: transparent;"><br></div><div style=3D"background-color: transparent;"><sp=
an>This can be tricky to solve, but I'm sure there's a solution. Good luck!=
</span></div><div style=3D"background-color: transparent;"><br></div><div><=
span></span></div><div style=3D"background-color:
transparent;">Anne</div><div><br></div> <div style=3D"font-family: 'times=
new roman', 'new york', times, serif; font-size: 12pt;"> <div style=3D"fon=
t-family: 'times new roman', 'new york', times, serif; font-size: 12pt;"> <=
div dir=3D"ltr"> <hr size=3D"1"> <font size=3D"2" face=3D"Arial"> <b><span=
style=3D"font-weight:bold;">From:</span></b> GALAMBOS Daniel <dancsa@da=
ncsa.hu><br> <b><span style=3D"font-weight: bold;">To:</span></b> openaf=
s-info@openafs.org <br> <b><span style=3D"font-weight: bold;">Sent:</span><=
/b> Thursday, December 26, 2013 9:48 AM<br> <b><span style=3D"font-weight: =
bold;">Subject:</span></b> [OpenAFS] Apache and Openafs<br> </font> </div> =
<div class=3D"y_msg_container"><br>=0AHi,<br><br>Our webservice built onto =
AFS, one node provide the static data, and<br>works as a proxy for PHP.<br>=
On this server, we have performance problem with AFS. This is a Debian<br>W=
heezy with afs client 1.6.1-3+deb7u1.<br><br>So we got problems, i cloned t=
he machine and started testing. I used<br>apache benchmark (ab) against a s=
imple html (w/o pictures or anything,<br>just text). If i downloaded it 200=
0 times with 50 thread i got high load<br>(18) and ~20 000 context switchin=
g in vmstat. The same file with 100<br>thread generated ~50 load.<br><br>af=
sd is started with the following options:<br>OPTIONS=3D"-stat 10000 -dcache=
10000 -daemons 6 -volumes 2048 -memcache<br>-chunksize 18 -rxpck 750 -rxma=
xmtu 1500 -prealloc 750"<br><br>cache size is: 3065648<br><br>During the te=
sts no other connection ( except apache status query 1/sec)<br>was made, th=
e same file was asked for 2000 times.<br><br>After reading old messages on =
this list, i decreased the
daemons to 3,<br>which caused a very little improvement. Reading the=
apache status i<br>noticed, that the apache spends 4-5 times more time in =
kernel space than<br>in users pace. When the same file hosted on the =
local filesystem the<br>avg response time decreased from 1800 ms to 50 ms a=
nd there are almost<br>no load.<br><br>Could you help me with this?<br><br>=
Thanks,<br><br>Dancsa<br><br>______________________________________________=
_<br>OpenAFS-info mailing list<br><a ymailto=3D"mailto:OpenAFS-info@openafs=
.org" href=3D"mailto:OpenAFS-info@openafs.org">OpenAFS-info@openafs.org</a>=
<br><a href=3D"https://lists.openafs.org/mailman/listinfo/openafs-info" tar=
get=3D"_blank">https://lists.openafs.org/mailman/listinfo/openafs-info</a><=
br><br><br></div> </div> </div> </div></body></html>
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