On Fri, 2009-01-23 at 16:30 +0800, Zhang, Yanmin wrote: > > I assume binding the client and the server to different physical CPUs > > also means that the SKB is always allocated on CPU 1 and freed on CPU > > 2? If so, we will be taking the __slab_free() slow path all the time on > > kfree() which will cause cache effects, no doubt. > > > > But there's another potential performance hit we're taking because the > > object size of the cache is so big. As allocations from CPU 1 keep > > coming in, we need to allocate new pages and unfreeze the per-cpu page. > > That in turn causes __slab_free() to be more eager to discard the slab > > (see the PageSlubFrozen check there). > > > > So before going for cache profiling, I'd really like to see an oprofile > > report. I suspect we're still going to see much more page allocator > > activity > Theoretically, it should, but oprofile doesn't show that. > > > there than with SLAB or SLQB which is why we're still behaving > > so badly here. > > oprofile output with 2.6.29-rc2-slubrevertlarge: > CPU: Core 2, speed 2666.71 MHz (estimated) > Counted CPU_CLK_UNHALTED events (Clock cycles when not halted) with a unit mask of 0x00 (Unhalted core cycles) count 100000 > samples % app name symbol name > 132779 32.9951 vmlinux copy_user_generic_string > 25334 6.2954 vmlinux schedule > 21032 5.2264 vmlinux tg_shares_up > 17175 4.2679 vmlinux __skb_recv_datagram > 9091 2.2591 vmlinux sock_def_readable > 8934 2.2201 vmlinux mwait_idle > 8796 2.1858 vmlinux try_to_wake_up > 6940 1.7246 vmlinux __slab_free > > #slaninfo -AD > Name Objects Alloc Free %Fast > :0000256 1643 5215544 5214027 94 0 > kmalloc-8192 28 5189576 5189560 0 0 ^^^^^^ This looks bit funny. Hmm. > :0000168 2631 141466 138976 92 28 > :0004096 1452 88697 87269 99 96 > :0000192 3402 63050 59732 89 11 > :0000064 6265 46611 40721 98 82 > :0000128 1895 30429 28654 93 32 -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html