"Paul Clements wrote:" > That's OK, we don't need to know. We really just want to know if there > are any outstanding writes for that chunk. We increment the chunk > counter for every write and decrement it when the write finishes. Now, I agree. I modified the bitmap so that when a page can't be got to make a mark on, then we count pending "writes" by summing one to a count for every attempted write to the zone covered by the missing page and subtracting one for every attempted clear. The bitmap reports "dirty" if the count is positive and the page for that zone is absent. I put the present code up at ftp://oboe.it.uc3m.es/pub/Programs/fr1-2.6.tgz I spent much of the morning checking that mark and clear attempts are balanced unless the write does not succeed. They are. This means that under memory pressure the bitmap not only fails only by losing precision (it did before), but now it can lose less precision, dropping to 256K instead of 4M precision, although I haven't implemented the final change to up the precision just yet. I made all the preparatory moves. Since it's friday I'll publish what I have. Under normal circumstances the count for each zone of the bitmap records the number of dirty bits. It's used to help free the bitmap pages at the right time, to stop pages accumulating to the max. Shucks .. I have to put them on a free list. I'll do that later too. Peter - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
