Christoph Lameter wrote: > Try to boot with > > slub_max_order=4 slub_min_objects=8 > > If that does not help increase slub_min_objects to 16. >
We are still seeing a 5% regression on TCP streaming with slub_min_objects set at 16 and a 10% regression for Volanomark, after increasing slub_min_objects to 16 and setting slub_max_order=4 and using the 2.6.21-rc7-mm2 kernel. The performance between slub_min_objects=8 and 16 are similar. >> We found that for Netperf's TCP streaming tests in a loop back mode, >> the TCP streaming performance is about 7% worse when SLUB is enabled >> on >> 2.6.21-rc7-mm1 kernel (x86_64). This test have a lot of sk_buff >> allocation/deallocation. > > 2.6.21-rc7-mm2 contains some performance fixes that may or may not be > useful to you. We've switched to 2.6.21-rc7-mm2 in our tests now. >> >> For Volanomark, the performance is 7% worse for Woodcrest and 12% >> worse for Clovertown. > > SLUBs "queueing" is restricted to the number of objects that fit in > page order slab. SLAB can queue more objects since it has true queues. > Increasing the page size that SLUB uses may fix the problem but then > we run into higher page order issues. > > Check slabinfo output for the network slabs and see what order is > used. The number of objects per slab is important for performance. The order used is 0 for the buffer_head, which is the most used object. I think they are 104 bytes per object. Tim - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/