On Tue, 5 Mar 2002, Dave Hansen wrote:
First of all, learn to use fscking line breaks.
> I posted the initial version of this last week. There was no discussion about the patch itself. I can only hope that no news is good news :)
>
> My first version of the patch reinitialized i_meta_lock for every read_inode call. This is not a correct way to do it. However, 2.4 does not have the capability to have fs-specific init_inode_once() functions. This probably meant altering the sb_ops structure if I wanted ext2_inode_info-specific initialization. To make the patch less intrusive, I put i_meta_lock right into the inode structure. I think that this is a good compromize between keeping ext2 code separated from VFS and patch simplicity. The lock is now initialized once per inode in fs/inode.c's init_once().
Denied. You can trivially do that in ext2_read_inode() and ext2_new_inode().
> I noticed the extra lock initializations because I was using lockmeter and kernprof while running dbench. I was seeing a large throughput decrease when my patch was applied, and kernprof told me that a big chunk of CPU time was being spent in lockmeter's rwlock_alloc. I have the feeling that I've hit a bottleneck in lockmeter's code spinning on locks which protect lockmeter's data structures.
>
> The patch is against 2.4.19-pre2. The patch significantly lowers BKL contention (50%) on a 2-way PII-300 running dbench 4. Dbench throughput is not significantly affected, but that is probably a function of my puny little machine more than the effectiveness of the patch. I'll have some results on a much more beefy 8-way PIII tomorrow. Earlier versions of the patch reduced BKL contention during dbench by 60% on the 8-way. CPU utilization spinning on the BKL has been as high as 40%.
ext2 patches _MUST_ get testing in 2.5 before they can go into 2.4. At
the very least a month, preferably - two. Until then consider them vetoed
for 2.4, no matter how BKL brigade feels about their crusade.
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This archive was generated by hypermail 2b29 : Thu Mar 07 2002 - 21:00:51 EST