Messages in this thread | | | Date | Wed, 5 Jan 2005 13:50:51 -0500 (EST) | From | Rik van Riel <> | Subject | Re: [PATCH][5/?] count writeback pages in nr_scanned |
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On Wed, 5 Jan 2005, Andrea Arcangeli wrote:
> Another unrelated problem I have in this same area and that can explain > VM troubles at least theoretically, is that blk_congestion_wait is > broken by design. First we cannot wait on random I/O not related to > write back. Second blk_congestion_wait gets trivially fooled by > direct-io for example. Plus the timeout may cause it to return too early > with slow blkdev.
Or the IO that just finished, finished for pages in another memory zone, or pages we won't scan again in our current go-around through the VM...
> blk_congestion_wait is a fundamental piece to get oom detection right > during writeback and unfortunately it's fundamentally fragile in 2.6 > (this as usual wasn't the case in 2.4).
Indeed ;(
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