Aaron Porter wrote:
On Tue, Jul 24, 2007 at 08:48:00PM +0200, Andi Kleen wrote:
Aaron Porter <[EMAIL PROTECTED]> writes:
I'm in the process up upgrading a pool of apache servers from
2.6.17.8 to 2.6.21.5, and we're seeing a pretty major change in behavior.
Under identical network load, 2.6.21 has a load average more than 3 times
higher, cpu 0 spends well over 90% of its time in interrupts (vs ~30%
under 2.6.17). When we hit 3k apache sessions, ksoftirqd eats 100% of cpu0
and our network traffic drops off rapidly. The end result is that 2.6.17
performs twice as well under this load.
Can you oprofile it?
# opreport -l
CPU: AMD64 processors, speed 1994.52 MHz (estimated)
Counted CPU_CLK_UNHALTED events (Cycles outside of halt state) with a unit mask
of 0x00 (No unit mask) count 100000
samples % app name symbol name
914379 48.8404 vmlinux-2.6.21.5 check_poison_obj
341920 18.2632 vmlinux-2.6.21.5 poison_obj
I bet you have CONFIG_DEBUG_SLAB turned off in your 2.6.17 kernel, and turned on
in your 2.6.21 kernel.
-- Chris
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