> i also want a way to clear part of the whole page cache by file id. :) understandably, kernel developers are don't high-prioritize this sort of not-useful-for-normal-work feature. > i also want a way to tell the cache distribution, how many for file A > and B, .... you should probably try mmaping the file and using mincore. come to think of it, mmap+madvise might be a sensible way to flush pages corresponding to a particular file, as well. > > I'm really surprised there isn't something in /proc you can use to > > clear or disable the cache. Would be very useful for benchmarking! I assume you noticed "blockdev --flushbufs", no? it works for me (ie, a small, repeated streaming read of a disk device will show pagecache speed). I think the problem is that it's difficult to dissociate readahead, writebehind and normal lru-ish caching. there was quite a flurry of activity around 2.4.10 related to this, and it left a bad taste in everyone's mouth. I think the main conclusion was that too much fanciness results in a fragile, more subtle and difficult-to-maintain system that performs better, true, but over a narrower range of workloads. regards, mark hahn sharcnet/mcmaster. - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
