Re: [Kiobuf-io-devel] RFC: Kernel mechanism: Compound event wait

From: Stephen C. Tweedie (
Date: Tue Feb 06 2001 - 19:36:29 EST


On Tue, Feb 06, 2001 at 07:25:19PM -0500, Ingo Molnar wrote:
> On Wed, 7 Feb 2001, Stephen C. Tweedie wrote:
> > No, it is a problem of the ll_rw_block interface: buffer_heads need to
> > be aligned on disk at a multiple of their buffer size. Under the Unix
> > raw IO interface it is perfectly legal to begin a 128kB IO at offset
> > 512 bytes into a device.
> then we should either fix this limitation, or the raw IO code should split
> the request up into several, variable-size bhs, so that the range is
> filled out optimally with aligned bhs.

That gets us from 512-byte blocks to 4k, but no more (ll_rw_block
enforces a single blocksize on all requests but that relaxing that
requirement is no big deal). Buffer_heads can't deal with data which
spans more than a page right now.

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This archive was generated by hypermail 2b29 : Wed Feb 07 2001 - 21:00:25 EST