Date: Mon, 17 Sep 2007 22:38:22 -0700 From: Julian Elischer <julian@elischer.org> To: Jeff Roberson <jroberson@chesapeake.net> Cc: arch@freebsd.org Subject: Re: Changing p_swtime and td_slptime to ticks Message-ID: <46EF644E.9050207@elischer.org> In-Reply-To: <20070917165657.B558@10.0.0.1> References: <20070917165657.B558@10.0.0.1>
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Jeff Roberson wrote: > Enclosed is a patch that fixes swapping with ULE. ULE has never > properly set p_swtime and td_slptime which are used by the > swapout/swapin code to select the appropriate thread to swap. I have not looked at in the depth required, but 2 points that I was unable to check to my satisfaction before I got called away for work.... 1/ the source of the ticks is a monotonically increasing count that never goes backwards or changes? 2/ nothing that used to be accounted in seconds becomes accounted for in ticks? > > In 4BSD these two variables are increment once per-second as schedcpu() > iterates over all threads. ULE does not have a once per-second loop > iterating over all threads. So I have changed p_swtime to p_swtick and > td_slptime to td_slptick. These record the value of 'ticks' when the > thread slept or was last swapped in or out. > > For backwards compatibility I leave the values in kinfo_proc with the > legacy meaning by subtracting from ticks and dividing by hz. I perform > a similar transformation in the swapout code to convert to seconds. > This change does make it possible to use sub-second granular decisions > in the swap code, however I'm not sure if that's really necessary. > > So that I did not disturb the 4BSD mechanism I kept the original > td_slptime in the td_sched area. It should be possible to use > td_slptick directly but especially this close to release I did not want > to change 4BSD. > > Feedback and testing welcome. > > Thanks, > Jeff > > > ------------------------------------------------------------------------ > > _______________________________________________ > freebsd-arch@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-arch > To unsubscribe, send any mail to "freebsd-arch-unsubscribe@freebsd.org"
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