On 12/24/2011 09:25 PM, Dennis Gilmore wrote:
Just throwing out what im seeing. lets see what ideas we can come up
with. performance is better than before. and seneca has done a great
job and put a lot of hard work into the reorg and im thankful for that.
We just have another bottleneck to address.
Allocating builders to individual rather than a single raid volume will
help dramatically. Since hfp/sfp F15 builds happen at the same time,
having 2 hfp disks and 2 sfp disks is a good start. Split it up again
by some other criteria- you want to try to ensure that any one builder
only causes one spindle to be used and any 2 builders each only cause 2
spindles to be used (1-to-1), and so forth. As long as any single
spindle isn't doing multiple simultaneous mock inits it should scale
pretty well. Allocate the large files the builders are using all at
once (no sparse files) to ensure large read/writes don't require seeks.
Use the async nfs export option if it isn't already in use. Disable
fs journaling (normally dangerous, but this is throw-away space). Use
noatime mounts if that won't break package builds checking filesystem
conformance. Once all that is done, tweak the number of nfsds such that
there are as many as possible without most of them going into deep
sleep. Perhaps somebody else can suggest some optimal sysctl and ext4fs
Brendan Conoboy / Red Hat, Inc. / blc(a)redhat.com