Re: 2.6.21 -> 2.6.22 & 2.6.23-rc8 performance regression

From: Eric Dumazet
Date: Mon Oct 01 2007 - 04:35:27 EST


Eric Dumazet a Ãcrit :
Denys a Ãcrit :
Well, i can play a bit more on "live" servers. I have now hot-swap server with
full gentoo, where i can rebuild any kernel you want, with any applied patch.
But it looks more like not overhead, load becoming high too "spiky", and it is
not just permantenly higher. Also it is not normal that all system becoming
unresposive (for example ping 127.0.0.1 becoming 300ms for period, when usage
softirq jumps to 100%).

Could you try a pristine 2.6.22.9 and some patch in secure_tcp_sequence_number() like :

--- drivers/char/random.c.orig 2007-10-01 10:18:42.000000000 +0200
+++ drivers/char/random.c 2007-10-01 10:19:58.000000000 +0200
@@ -1554,7 +1554,7 @@
* That's funny, Linux has one built in! Use it!
* (Networks are faster now - should this be increased?)
*/
- seq += ktime_get_real().tv64;
+ seq += ktime_get_real().tv64 / 1000;
#if 0
printk("init_seq(%lx, %lx, %d, %d) = %d\n",
saddr, daddr, sport, dport, seq);
On 32 bits machine, replace the divide by a shift to avoid a linker error (undefined reference to `__divdi3'):

seq += ktime_get_real().tv64 >> 10;





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