On Mon, 19 Jul 1999 12:46:24 -0400 (EDT), Chuck Lever <cel@monkey.org>
said:
> On Sun, 18 Jul 1999, Jamie Lokier wrote:
>> The net result is once the readahead window opens up enough,
>> filemap_nopage never waits on I/O, not even once per cluster. With the
>> code in place it might even be worth using readahead that's smaller than
>> the random access readaround cluster size. More I/Os, less memory used.
> more i/o's means less disk scalability, IMO.
Correct. 2.2 is substantially faster than 2.0 on low-memory machines,
primarily because the benefit of doing fewer swap and paging IOs more
than outweighs the extra memory used by the speculative IO.
--Stephen
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