Date: Mon, 22 Sep 1997 12:39:44 -0600 (MDT) From: Nate Williams <nate@mt.sri.com> To: "Justin T. Gibbs" <gibbs@plutotech.com> Cc: Nate Williams <nate@mt.sri.com>, current@freebsd.org Subject: Re: cvs commit: src/sys/conf files src/sys/dev/vx if_vx.c if_vxreg.h src/sys/i386/apm apm.c src/sys/i386/conf GENERIC files.i386 src/sys/i386/eisa 3c5x9.c aha1742.c aic7770.c bt74x.c eisaconf.c eisaconf.h if_fea.c if_vx_eisa.c src/sys/i386/i386 autoconf.c ... Message-ID: <199709221839.MAA01809@rocky.mt.sri.com> In-Reply-To: <199709220548.XAA08824@pluto.plutotech.com> References: <199709220505.XAA29116@rocky.mt.sri.com> <199709220548.XAA08824@pluto.plutotech.com>
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> In performing the conversion of all the client code, it became quite > obvious that the common case is to schedule a timeout that will be > canceled before it expires and that the lifetime of a timeout is quite > short. Is 'short' shorter than a single softclock()? If not, then we still need to do more work than we used to do. And, if we have 2 ticks, 'assuming all things we're equal' the new code could be the same speed as the old code. (Obviously bogus explanation follows): Old code: 1) timeout = O(x) ~= 10 seconds 2) untimeout = O(x) ~= 10 seconds 3) softclock = O(1) ~= 1 second So, assuming we call a timeout, get 2 softclock updates, and then call untimeout we get: 10 + 1 + 1 + 10 = 22 seconds. New code: 1) timeout = O(1) ~= 1 seconds 2) untimeout = O(1) ~= 1 seconds 3) softclock = O(n) ~= 10 second The same as above: 1 + 10 + 10 + 1 = 22 seconds. Again, this is so obviously bogus that I hate to even mention it, but it explains what I'm trying to say. Depending on *how often* and *how long* each of the operations takes, the new solution may not be a win. I'll stop for now, since this is as much a learning experience for me as anything, and I don't want to wear out my welcome. :) :) Nate
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