• Nick Piggin's avatar
    [PATCH] fix AS crappy performance · 41b986b6
    Nick Piggin authored
    A while ago some guy complained that his server connections / sec was
    way down due to AS. The server would fork a process which would then read
    some tiny bit of random data and hang around for a while doing nothing.
    This defeated all AS's heuristics, and due to a new process being a good
    anticipation candidate by default, his performance went bad.
    
    The fix was just to treat new processes as being unsuitable for
    anticipation. Fixed. Unfortunately ls, cat, grep, small programs
    starting up, find | xargs, etc only submit a couple of requests, and they
    really want anticipation to be on.
    
    This patch keeps a simple goodness value per queue based on how successful
    anticipation has been for new processes.
    41b986b6
as-iosched.c 48.1 KB