Date: Mon, 9 Feb 2004 09:42:48 -0800 (PST) From: Nate Lawson <nate@root.org> To: Bruce Evans <bde@zeta.org.au> Cc: Tim Robbins <tjr@FreeBSD.org> Subject: Re: cvs commit: src/sys/kern kern_resource.c Message-ID: <20040209094012.C73740@root.org> In-Reply-To: <20040208074351.Y58537@gamplex.bde.org> References: <200402061930.i16JUCpa011145@repoman.freebsd.org> <20040208074351.Y58537@gamplex.bde.org>
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On Sun, 8 Feb 2004, Bruce Evans wrote: > On Sat, 7 Feb 2004, Tim Robbins wrote: > > On Fri, Feb 06, 2004 at 11:30:12AM -0800, John Baldwin wrote: > > > > > jhb 2004/02/06 11:30:12 PST > > > > > > FreeBSD src repository > > > > > > Modified files: > > > sys/kern kern_resource.c > > > Log: > > > - Correct the translation of old rlimit values to properly handle the old > > > RLIM_INFINITY case for ogetrlimit(). > > > - Use %jd and intmax_t to output negative time in usec in calcru(). > > > - Rework getrusage() to make a copy of the rusage struct into a local > > > variable while holding Giant and then do the copyout from the local > > > variable to avoid having to have the original process rusage struct > > > locked while doing the copyout (which would not be safe). This also > > > includes a few style fixes from Bruce to getrusage(). > > > > Thanks (from the one who added the XXX comment). Can't we use the > > proc lock here though? > > calcru() takes about 4.5 usec on a Celeron 366 > with a TSC timecounter, and this is too long to hold a spin lock since, > while it is not too bad in absolute terms, it scales to 100+ usec on > old machines that used to have an interrupt latency of much smaller > than 100 usec. Another way to look at the relative largeness of 4.5 > usec: vfork()+exit()+wait() for a small process takes about 86 usec > on a Celeron 366, and 4.5 usec of that is for calcru(). What if calcru() were postponed until the process lifetime was a minimum quantum? This sounds like we should be concerned about the vfork/exec case if your above example applies. -Nate
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