[Catalyst] Resolving performance issues.

[Bill Moseley]

This is a question for the sysadmins out there.

My application is running fine on my development machine[1], but when
moved to a Dreamhost dedicated server[1] it's quite slow.

I'm looking for suggestions on what I might use to get some metrics
before talking to Dreamhost about the issue (just saying "It's slow"
is not very persuasive).

My machine can have its load average up at 1 and is still much faster
than the server with load average < 0.1 at start of a request.  vmstat
shows no swapping[4], so memory is not an issue it seems.

Not a very telling test, but this does show the relative difference in
speed by using apache's ab.

Just running the test server, not in debug mode or forking with apache
ab with -n 100 -c 1 I see the following.  All running on localhost.


                          Request/second
                        (we like big numbers!)
                      Athlon             Dreamhost
                    --------------     -------------
Static content[2]       30.5               6.5
(2264 bytes)

One database             8.6               1.2
access (8230 bytes)

Very complex page[3]     1.5               0.27


The database is currently 7.4 on both machines -- soon to move to
8.1.3 which will help a little.


[1] Some of the basic specs are (most from /etc/cpuinfo and dmesg):

                Development         Dreamhost Servre
                ---------------     ----------------------
    CPU         Athlon XP1800+      Xeon
    Mhz         1150.591            1793.936
    cache       256KB               512KB
    bogomips    2260.99             3565.15
    RAM         1GB                 .5GB
    OS          Deb Unstable        Deb Sarge
    Kernel      2.6.6               2.4.28
    Tasks       115                 214
    fs          xfs atime           ext3 noatime, nodiratime

Tasks is just a quick snapshot of the number of processes top reports.




[2] This is not a question about how to best server static content.
That's putting an open file handle in $c->res->body.

[3] DBI_TRACE output | grep "execute" | wc -l = 59 execute() calls

[4] vmstat during the "Very complex" run on Dreamhost

procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in    cs us sy id wa
 2  0 314100  11508  94372 117756    1    1     6     9    4     7 13  4 83  0
15  0 314100   7540  94392 118236    0    0   240   142  459   850 90  9  0  0
13  0 314100   6544  94392 118292    0    0    28     0  325   835 94  6  0  0
 2  0 314100   6868  94444 118420    0    0    64   158  352   965 89 11  0  0
12  0 314100  12092  94452 118708    0    0   148     0  332  1011 87 13  0  0
13  0 314100  10232  94468 118836    0    0    64   112  376   900 88 12  0  0
17  1 314100   6800  94484 119092    0    0   128    44  343   858 90 10  0  0
 3  0 314100  11636  94512 119092    0    0     0    20  279   906 87 13  0  0
16  0 314100  11408  94532 119220    0    0    64   112  308   931 90 10  0  0
15  0 314100  10676  94532 119224    0    0     0     0  267   951 84 16  0  0
13  0 314100   9032  94552 119352    0    0    64   160  278   904 87 13  0  0
13  0 314100  10100  94588 119480    0    0    64    64  262   856 86 14  0  0
16  0 314100   9436  94588 119748    0    0   134     0  340   980 87 13  0  0
14  0 314100   6756  94604 119752    0    0     0   112  257   789 81 19  0  0
16  0 314100   5292  94600 119880   14    0    78     0  333   746 85 15  0  0
12  0 314100  11620  94672 119880    0    0     0   190  286   968 85 15  0  0
12  0 314100  11580  94672 120008    0    0    64     0  246   944 86 14  0  0
13  0 314100   7804  94672 120008    0    0     0     0  249   811 83 17  0  0


-- 
Bill Moseley
moseley at hank.org