Re: 2.6.1 slower than 2.4, smp/scsi/sw-raid/reiserfs

Nick Piggin
2004-02-02T23:36:55Z

Philip Martin wrote:

>Nick Piggin <piggin@cyberone.com.au> writes:
>
>
>>Another thing I just saw - you've got quite a lot of memory in
>>buffers which might be something going wrong.
>>
>>When the build finishes and there is no other activity, can you
>>try applying anonymous memory pressure until it starts swapping
>>to see if everything gets reclaimed properly?
>>
>
>How do I apply anonymous memory pressure?
>
>

Well just run something that uses a lot of memory and doesn't
do much else. Run a few of these if you like:

#include <stdlib.h>
#include <unistd.h>
#define MEMSZ (64 * 1024 * 1024)
int main(void)
{
int i;
char *mem = malloc(MEMSZ);
for (i = 0; i < MEMSZ; i+=4096)
mem[i] = i;
sleep(60);
return 0;
}

>>Was each kernel freshly booted and without background activity
>>before each compile?
>>
>
>Each kernel was freshly booted. There were a number of daemons
>running, and I was running X, but these don't appear to use much
>memory or CPU and the network was disconnected. Just after a boot
>there is lots of free memory, but in normal operation the machine uses
>its memory, so to make it more like normal I ran "find | grep" before
>doing the build. Then I ran make clean, make, make clean, make and
>took numbers for the second make.
>
>You can have the numbers straight after a boot as well. In this case
>I rebooted, logged in, ran make clean and make -j4.
>
>I can hear disk activity on this machine. During a 2.4.24 build the
>activity happens in short bursts a few seconds apart. During a 2.6.1
>build it sounds as if there is more activity, with each burst of
>activity being a little longer. However that just the impression I
>get, I haven't tried timing anything, I may be imagining it.
>
>

Thanks. Much the same, isn't it?
Can you try booting with the kernel argument: elevator=deadline
and see how 2.6 goes?

Andrew, any other ideas?