On Sun, Jan 28, 2007 at 02:43:25PM +0000, Christoph Hellwig wrote: > On Sun, Jan 28, 2007 at 12:51:18PM +0100, Peter Zijlstra wrote: > > This patch-set breaks up the global file_list_lock which was found to be a > > severe contention point under basically any filesystem intensive workload. > > Benchmarks, please. Where exactly do you see contention for this? > > > filesystem intensive workload apparently means namespace operation heavy > workload, right? The biggest bottleneck I've seen with those is dcache lock. > > Even if this is becoming a real problem there must be simpler ways to fix > this than introducing various new locking primitives and all kinds of > complexity.
One good way to fix scalability without all this braindamage is to get rid of sb->s_files. Current uses are: - fs/dquot.c:add_dquot_ref() This performs it's actual operation on inodes. We should be able to check inode->i_writecount to see which inodes need quota initialization. - fs/file_table.c:fs_may_remount_ro() This one is gone in Dave Hansens per-mountpoint r/o patchkit - fs/proc/generic.c:proc_kill_inodes() This can be done with a list inside procfs. - fs/super.c:mark_files_ro() This one is only used for do_emergency_remount(), which is and utter hack. It might be much better to just deny any kind of write access through a superblock flag here. - fs/selinuxfs.c:sel_remove_bools() Utter madness. I have no idea how this ever got merged. Maybe the selinux folks can explain what crack they were on when writing this. The problem would go away with a generic rewoke infrastructure. Once sb->s_files is gone we can also kill of fu_list entirely and replace it by a list head entirely in the tty code and make the lock for it per-tty. - 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/