On Sat, 4 Aug 2001, Rik van Riel wrote:
> On Fri, 3 Aug 2001, Linus Torvalds wrote:
>
> > Please just remove the code instead. I don't think it buys you anything.
>
> IIRC you applied the patch introducing that logic because it
> gave a 25% performance increase under some write intensive
> loads (or something like that).
That's the batching code, which is somewhat intertwined with the same
code.
The batching code is a separate issue: when we free the requests, we don't
actually make them available as they get free'd (because then the waiters
will trickle out new requests one at a time and cannot do any merging
etc).
Also, the throttling code probably _did_ make behaviour nicer back when
"sync()" used to use ll_rw_block(). Of course, now most of the IO layer
actually uses "submit_bh()" and bypasses this code completely, so only the
ones that still use it get hit by the unfairness. What a double whammy ;)
Linus
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This archive was generated by hypermail 2b29 : Tue Aug 07 2001 - 21:00:31 EST