This patchset has grown quite a bit - it started out as a "convert the buffer cache to rbtrees" patch, and has gotten bigger as I peeled the onion from one bottleneck to another. Performance numbers here are 8-way fs_mark create to 50M files, and 8-way rm -rf to remove the files created. wall time fs_mark rate 2.6.36-rc4: create: 13m10s 65k file/s unlink: 23m58s N/A The first set of patches are generic infrastructure changes that address pain points the rbtree based buffer cache introduces. I've put them first because they are simpler to review and have immediate impact on performance. These patches address lock contention as measured by the kernel lockstat infrastructure. xfs: single thread inode cache shrinking. - prevents per-ag contention during cache shrinking xfs: reduce the number of CIL lock round trips during commit - reduces lock traffic on the xc_cil_lock by two orders of magnitude xfs: remove debug assert for per-ag reference counting xfs: lockless per-ag lookups - hottest lock in the system with buffer cache rbtree path - converted to use RCU. xfs: convert inode cache lookups to use RCU locking xfs: convert pag_ici_lock to a spin lock - addresses lookup vs reclaim contention on pag_ici_lock - converted to use RCU. xfs: don't use vfs writeback for pure metadata modifications - inode writeback does not keep up with dirtying 100,000 inodes a second. Avoids the superblock dirty list where possible by using the AIL as the age-order flusher. Performance with these patches: 2.6.36-rc4 + shrinker + CIL + RCU: create: 11m38s 80k files/s unlink: 14m29s N/A Create rate has improved by 20%, unlink time has almost halved. On large numbers of inodes, the unlink rate improves even more dramatically. The buffer cache to rbtree series current stands at: xfs: rename xfs_buf_get_nodaddr to be more appropriate xfs: introduced uncached buffer read primitve xfs: store xfs_mount in the buftarg instead of in the xfs_buf xfs: kill XBF_FS_MANAGED buffers xfs: use unhashed buffers for size checks xfs: remove buftarg hash for external devices - preparatory buffer cache API cleanup patches xfs: convert buffer cache hash to rbtree - what it says ;) - includes changes based on Alex's review. xfs; pack xfs_buf structure more tightly - memory usage reduction, means adding the LRU list head is effectively memory usage neutral. xfs: convert xfsbud shrinker to a per-buftarg shrinker. xfs: add a lru to the XFS buffer cache - Add an LRU for reclaim xfs: stop using the page cache to back the buffer cache - kill all the page cache code 2.6.36-rc4 + shrinker + CIL + RCU + rbtree: create: 9m47s 95k files/s unlink: 14m16s N/A Create rate has improved by another 20%, unlink rate has improved marginally (noise, really). There are two remaining parts to the buffer cache conversions: 1. work out how to efficiently support block size smaller than page size. The current code works, but uses a page per sub-apge buffer. A set of slab caches would be perfect for this use, but I'm not sure that we are allowed to use them for IO anymore. Christoph? 2. Connect up the buffer type sepcific reclaim priority reference counting and convert the LRU reclaim to a cursor based walk that simply drops reclaim reference counts and frees anything that has a zero reclaim reference. Overall, I can swap the order of the two patch sets, and the incremental performance increases for create are pretty much identical. For unlink, te benefit comes from the shrinker modification. For those that care, the rbtree patch set in isolation results in a time of 4h38m to create 1 billion inodes on my 8p/4GB RAM test VM. I haven't run this test with the RCU and writeback modifications yet. Moving on from this point is to start testing against Nick Piggin's VFS scalability tree, aѕ the inode_lock and dcache_lock are now the performance limiting factors. That will, without doubt, bring new hotspots out in XFS so I'll be starting this cycle over again soon. Overall diffstat at this point is: fs/xfs/linux-2.6/kmem.h | 1 + fs/xfs/linux-2.6/xfs_buf.c | 588 ++++++++++++++-------------------------- fs/xfs/linux-2.6/xfs_buf.h | 61 +++-- fs/xfs/linux-2.6/xfs_iops.c | 18 +- fs/xfs/linux-2.6/xfs_super.c | 11 +- fs/xfs/linux-2.6/xfs_sync.c | 49 +++- fs/xfs/linux-2.6/xfs_trace.h | 2 +- fs/xfs/quota/xfs_qm_syscalls.c | 4 +- fs/xfs/xfs_ag.h | 9 +- fs/xfs/xfs_buf_item.c | 3 +- fs/xfs/xfs_fsops.c | 11 +- fs/xfs/xfs_iget.c | 46 +++- fs/xfs/xfs_inode.c | 22 +- fs/xfs/xfs_inode_item.c | 9 - fs/xfs/xfs_log.c | 3 +- fs/xfs/xfs_log_cil.c | 116 +++++---- fs/xfs/xfs_log_recover.c | 18 +- fs/xfs/xfs_mount.c | 126 ++++----- fs/xfs/xfs_mount.h | 2 + fs/xfs/xfs_rtalloc.c | 29 +- fs/xfs/xfs_vnodeops.c | 2 +- 21 files changed, 502 insertions(+), 628 deletions(-) So it is improving performance, removing code and fixing longstanding bugs all at the same time. ;) _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
