Re: [Lse-tech] lockmeter results comparing 2.4.17, 2.5.3, and 2.5.5

[Martin J. Bligh]

> 2.5.5: 
> 
>        8.6%  1.6us( 100ms)   30us(  86ms)( 9.4%) 783373441 91.4%  8.6% 0.00%  *TOTAL*

Whilst it's great to see BKL contention going down, this:

0.16% 0.25%  0.7us( 100ms)  252us(  86ms)(0.02%)   6077746 99.8% 0.25%    0%  inode_lock
 0.03% 0.11%  0.6us(  55us)  2.1us( 9.9us)(0.00%)   1322338 99.9% 0.11%    0%    __mark_inode_dirty+0x48
 0.00%    0%  0.7us( 5.9us)    0us                      391  100%    0%    0%    get_new_inode+0x28
 0.00% 0.22%  2.5us(  50us)  495us(  28ms)(0.00%)     50397 99.8% 0.22%    0%    iget4+0x3c
 0.03% 0.28%  0.6us(  26us)   30us(  58ms)(0.00%)   1322080 99.7% 0.28%    0%    insert_inode_hash+0x44
 0.04% 0.29%  0.5us(  39us)  332us(  86ms)(0.01%)   2059365 99.7% 0.29%    0%    iput+0x68
 0.03% 0.30%  0.7us(  57us)  422us(  77ms)(0.01%)   1323036 99.7% 0.30%    0%    new_inode+0x1c
 0.03%  8.3%   63ms( 100ms)  3.8us( 3.8us)(0.00%)        12 91.7%  8.3%    0%    prune_icache+0x1c
 0.00%    0%  1.0us( 5.2us)    0us                       34  100%    0%    0%    sync_unlocked_inodes+0x10
 0.00%    0%  1.0us( 2.4us)    0us                       93  100%    0%    0%    sync_unlocked_inodes+0x110

looks a little distressing - the hold times on inode_lock by prune_icache 
look bad in terms of latency (contention is still low, but people are still 
waiting on it for a very long time). Is this a transient thing, or do people 
think this is going to be a problem?

Martin.