Messages in this thread |  | | Date | Tue, 6 Feb 2001 21:25:03 +0100 | From | Christoph Hellwig <> | Subject | Re: [Kiobuf-io-devel] RFC: Kernel mechanism: Compound event wait |
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On Tue, Feb 06, 2001 at 11:32:43AM -0800, Linus Torvalds wrote: > Traditionally, a "bh" is only _used_ for small areas, but that's not a > "bh" issue, that's a memory management issue. The code should pretty much > handle the issue of a single 64kB bh pretty much as-is, but nothing > creates them: the VM layer only creates bh's in sizes ranging from 512 > bytes to a single page. > > The IO layer could do more, but there has yet to be anybody who needed > more (becase once you hit a page-size, you tend to get into > scatter-gather, so you want to have one bh per area - and let the > low-level IO level handle the actual merging etc).
Yes. That's one disadvantage blown away.
The second is that bh's are two things:
- a cacheing object - an io buffer
This is not really an clean appropeach, and I would really like to get away from it.
Christoph
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