On Thu, May 11, 2000 at 12:23:19AM -0700, Linus Torvalds wrote:

> Hmm..
> 
>  Having tested some more, the "wait for locked buffer" logic in
> fs/buffer.c (sync_page_buffers()) seems toserialize thingsawhole lote more
> than I initially thought..
> 
> Does it act the way you expect if you change the
> 
> 	if (buffer_locked(p))
> 		__wait_on_buffer(p);
> 	else if (buffer_dirty(p))
> 		ll_rw_block(..
> 
> to a simpler
> 
> 	if (buffer_dirty(p) && !buffer_locked(p))
> 		ll_rw_block(..
> 
> which doesn't endup serializing the IO all the time?

A little bit better!  203 vmstat-line-seconds before, now 155
vmstat-line-seconds to complete.  It seems to be doing a better job like
this, but still doesn't write out in blocks like it used to:

2.3.99pre7-9 vanilla:

 0 1 1   32   2212   216 112424   0   4   609   527  239   112   5   8  87
 0 1 1   32   3004   216 111472   0   4   608   540  327   120   5   7  87
 0 1 1   32   3008   232 111252   0   4   768  1083  405   252   3  11  86
 0 1 1   32   1964   240 112144   0   0   594   570  422   222   3  14  83
 1 1 1   60   2932   248 111164   0  36   661   586  349   226   3  13  84

2.3.99pre7-9 with above adjustment:

 0 1 1   64   3032   272 110768   0   0   833   628  414   338   5  28  67
 0 1 1   64   2608   276 111040   0   0   769  1081  440   268   3  24  72
 0 1 1   64   2684   284 110804   0   0   847  1089  370   280   6  12  82
 0 1 0   64   2832   276 110796   0   0   706   558  384   193   7  11  82
 0 1 1  136   1280   284 112440   0  72   911  1084  494   251   6  13  81

Also, it's still not as fast as classzone-27 writing out, and CPU use is
still a bit higher:

2.3.99pre7-8 classzone-27:

 0 1 0  540   2852   272 110796   0   0  1089  1000  465   148   7   5  88
 0 1 0  540   2980   264 110676   0   0  1423  1500  380   140   7   7  86
 0 1 0  540   2584   272 111068   0   0  1059  1000  421   146   9   3  88
 0 1 0  988   2556   276 111524   0 448  1473  1612  523   148  10   6  84
 1 0 0  988   2704   264 111408   0   0  1135  1000  423   163   6   6  88

(All from random areas, sorry... it might be a good idea to read all of
the output in the attachment.)

I attached vmstat-3.txt, the full output with "2.3.99pre7-9 with above
adjustment".

Simon-

[  Stormix Technologies Inc.  ][  NetNation Communications Inc. ]
[       sim@stormix.com       ][       sim@netnation.com        ]
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