Messages in this thread |  | | | Date | Tue, 03 Feb 2004 10:36:18 +1100 | | From | Nick Piggin <> | | Subject | Re: 2.6.1 slower than 2.4, smp/scsi/sw-raid/reiserfs |
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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?
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