Messages in this thread | | | From | Ed Tomlinson <> | Subject | Re: [PATCH] 2.6.0 - Watchdog patches (BK consistency checks) | Date | Wed, 31 Dec 2003 11:33:58 -0500 |
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On December 30, 2003 03:16 pm, Andy Isaacson wrote: > On Tue, Dec 30, 2003 at 12:56:32PM -0700, Eric D. Mudama wrote: > > On Tue, Dec 30 at 13:13, Andy Isaacson wrote: > > >On Tue, Dec 30, 2003 at 08:36:15AM -0500, Ed Tomlinson wrote: > > >The consistency check definitely should not take 15 minutes. It should > > >be (much) less than 30 seconds. What is the hardware you're running on? > > > > > >I'm running on an Athlon 2 GHz (XP 2400+) with 512MB and a 7200RPM IDE > > >disk, and I can do a complete clone (with full data copy and consistency > > >check) of the 2.4 tree in 1:40. That was with cold caches; with the > > >sfile copies and "checkout:get", a half-gig isn't enough to cache > > >everything. The consistency check is about 19 seconds (bk -r check > > > -acv). > > > > For what it is worth: > > > > AMD Duron 950MHz, 768MB RAM > > 7200RPM 80GB Quantum Viper IDE drive, 26% full > > > > phat-penguin:~/src/linux-2.5> time bk -r check -acv > > 100% |=================================================================| > > OK 42.710u 5.770s 2:04.63 38.8% 0+0k 0+0io 74078pf+0w > > > > over 2 minutes of wall time, 42 seconds of "user" time... (if I'm reading > > it right), without primed disk caches. > > > > The 2nd run, half a minute later: > > > > phat-penguin:~/src/linux-2.5> time bk -r check -acv > > 100% |=================================================================| > > OK 41.900u 3.080s 0:45.53 98.7% 0+0k 0+0io 74078pf+0w > > > > > > ...would appear to show that BK's checksumming, on my system, is > > constrained near 41 seconds of calculation time, and the difference > > between the user and the wall-clock time is basically time spent > > waiting for the disk to do all its reads. > > > > > > I guess in that case, it'd be interesting to see what the user and > > wall times were for the original poster who reported a 15+ minute > > integrity check. > > That's basically right, except that if you don't have enough memory to > keep bk's working set in memory, then you're paging and performance > starts to suck. > > I didn't realize that the cpu-bound portion of the check would scale so > closely with CPU speed, but it looks like the scaling is almost dead-on; > 18.4/41.9 = .439 > 950/2000 = .475 > > So I was wrong to say "less than 30 seconds". "If you have a fast CPU > and enough memory", I guess. But the memory matters a lot more than the > CPU.
Here are the numbers from my box:
oscar% cd /usr/src/linux oscar% time bk -r check -acv 100% |=================================================================| OK bk -r check -acv 80.63s user 16.18s system 21% cpu 7:32.06 total
oscar% time bk clone -ql linux yy bk clone -ql linux yy 77.57s user 23.49s system 17% cpu 9:50.51 total
Ed
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