On Tue, Mar 02, 2010 at 06:34:51PM +0000, Alan Cox wrote: > > For reasons that are not particularly clear to me, tty_buffer_alloc() is > > called far more frequently in 2.6.33 than in 2.6.24. I instrumented the > > function to print out the size of the buffers allocated, booted under > > qemu and would just "cat /bin/ls" to see what buffers were allocated. > > 2.6.33 allocates loads, including high-order allocations. 2.6.24 > > appeared to allocate once and keep silent. > > The pty layer is using them now and didn't before. That will massively > distort your numhers. > That makes perfect sense. It explains why only one allocation showed up because it must belong to the tty attached to the serial console. Thanks Alan. > > While there have been snags recently with respect to high-order > > allocation failures in recent kernels, this might be one of the cases > > where it's due to subsystems requesting high-order allocations more. > > The pty code certainly triggered more such allocations. I've sent Greg > patches to make the tty buffering layer allocate sensible sizes as it > doesn't need multiple page allocations in the first place. > Greg, what's the story with these patches? -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>