[Csync2] linux kernel cpu optimization

[Vincent Régnard]

Hi all,

I have performance issues using csync2 on SMP system
I csync2 a big disk whith ~ 1 million files, no frequent updates, only 
small changes on ext3 fs + linux 2.6.16 kernel. Cyncing is very long 
(somtimes half an hour), hardware is efficient, process should certainly 
run better than that.
I forced all disk interrupt on CPU1 using the /proc/irq/IRQ/smp_affinity 
trick, but I observe that CPU1 remains in waiting state too much as 
shown by the top above (about 50% on average) when csync is checking the 
whole file system tree.

I execute csync2 with a nice priority (level 5)
top - 12:54:08 up 6 days,  1:33,  4 users,  load average: 0.80, 0.65, 0.66
Tasks: 139 total,   4 running, 135 sleeping,   0 stopped,   0 zombie
Cpu0  :  0.0% us,  9.4% sy,  2.3% ni, 66.9% id, 21.4% wa,  0.0% hi,  0.0% si
Cpu1  : 11.3% us, 31.7% sy,  6.3% ni,  0.0% id, 49.7% wa,  0.3% hi,  0.7% si
Mem:    903100k total,   893576k used,     9524k free,    68436k buffers
Swap:  1959920k total,        8k used,  1959912k free,   312908k cached

How can I improve that situation ? Can I tweek kernel params to change 
that or is it csync2 internals specific ? NB: I do not have similar 
behaviour with other heavy processes (such as zipping/unzipping huge 
files, backup process etc..).

-- 
Vincent Régnard
vregnard at tbs-internet.com
TBS-internet.com
027 630 5902


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