Messages in this thread | | | Date | Wed, 1 Dec 1999 10:15:12 +0100 (CET) | From | Ingo Molnar <> | Subject | Re: [CFT][PATCH] block_write_*_buffer rewrite |
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On Tue, 30 Nov 1999, Alexander Viro wrote:
> Patch merges most of block_write_{partial,cont}_page and fixes a > couple of bad bugs in the latter. It should fix the problems with > write-beyond-EOF on FAT and HPFS and it cleans the code up. [...]
looks good, but i think you have removed an important optimization: overlapping the issuing/finishing of read requests with copying memory, on 1k filesystems. This should not matter much on bigger boxes, but on smaller ones i've seen a definite advantage. So it's fine (and wanted) to issue read requests first (the old version didnt do this), but you are waiting for them to finish synchronously - this should be interleaved with memory copies. Also there is a deadlock situation which David Miller noticed some time ago (i think this is still present): just try read()-ing a file into a freshly mmap()-ed memory area. (where the mmap-ed page is the same as the read() page.) Legal combination, instant stuck process.
-- mingo
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