On 5 March 2011 21:05, Jeremy Chadwick <free...@jdc.parodius.com> wrote: > On Sat, Mar 05, 2011 at 08:49:46PM -0500, ill...@gmail.com wrote: >> On 5 March 2011 20:43, Jeremy Chadwick <free...@jdc.parodius.com> wrote: >> > On Sat, Mar 05, 2011 at 03:01:40PM -1000, Clifton Royston wrote: >> >> On Sat, Mar 05, 2011 at 03:45:14PM -0800, Jeremy Chadwick wrote: >> >> > This is a strange one, and the more I started debugging it (starting >> >> > with truss, comparing fast vs. slow results, where all that appears >> >> > different is read() operations are taking a lot longer -- I haven't had >> >> > time to check with ktrace yet), the more strange it got: that's when I >> >> > found out the behaviour changes depending on if you're a user or root. >> >> > >> >> > Easy to reproduce: >> >> > >> >> > - grep -r string /usr/src, as non-root, is fast >> >> > - grep -r -i string /usr/src, as non-root, is 8x slower than without -i >> >> >> >> From your results below, I think you mean *80* x slower! >> > >> > Oops; yes, typo on my part. I was never any good at math either! ;-) >> > >> >> > - grep -r string /usr/src, as root, is fast >> >> > - grep -r -i string /usr/src, as root, is fast >> >> >> >> I can not reproduce this on 7.3-RELEASE-p4; I get consistent results >> >> between root and non-root, with -i being only marginally slower (about >> >> 15%) for each; results below. >> > >> > Your results look more or less like what I see on the 4th system (the >> > 7.0-STABLE one). I believe the speed difference there (and on your >> > system) is justified, as I would imagine strcasecmp() a tiny bit slower >> > than strcmp(). But an 80x slowdown is completely unacceptable, >> > especially given the conditions. >> > >> > My first thought was "compiler optimisation bug?", which I suppose could >> > still be the case, but I don't know how root vs. non-root would change >> > that behaviour, not to mention only when -i was specified. >> > >> > Using 'truss -d' it looks like the slowdown is happening on read(2), >> > which makes me very concerned, as it could indicate something odd going >> > on with CAM? Sadly I cannot (for many reasons) get rid of ahci.ko on >> > any of those 3 systems, so I can't compare stock ata(4) to ahci.ko >> > easily on the same system. >> > >> >> On my 8.2-RELEASE system using ahci (built into the custom >> kernel) I don't notice your observed slowdown, so unless ahci >> is radically different on -STABLE I doubt it's the cause. > > There are two versions of AHCI available in FreeBSD: ahci.ko (which is > AHCI<->CAM) and ataahci.ko (which is AHCI support under ata(4) natively > and does not use CAM). Which of the two are you using?
I have device ahci in my kernel, ataahci, not. > sysctl -a | grep ahci dev.ahci.0.%desc: ATI IXP600 AHCI SATA controller dev.ahci.0.%driver: ahci dev.ahci.0.%location: slot=18 function=0 handle=\_SB_.PCI0.SATA dev.ahci.0.%pnpinfo: vendor=0x1002 device=0x4380 subvendor=0x1179 subdevice=0xff68 class=0x01018f dev.ahci.0.%parent: pci0 dev.ahcich.0.%desc: AHCI channel dev.ahcich.0.%driver: ahcich dev.ahcich.0.%location: channel=0 dev.ahcich.0.%parent: ahci0 dev.ahcich.1.%desc: AHCI channel dev.ahcich.1.%driver: ahcich dev.ahcich.1.%location: channel=1 dev.ahcich.1.%parent: ahci0 dev.ahcich.2.%desc: AHCI channel dev.ahcich.2.%driver: ahcich dev.ahcich.2.%location: channel=2 dev.ahcich.2.%parent: ahci0 dev.ahcich.3.%desc: AHCI channel dev.ahcich.3.%driver: ahcich dev.ahcich.3.%location: channel=3 dev.ahcich.3.%parent: ahci0 HTH -- -- _______________________________________________ freebsd-stable@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscr...@freebsd.org"
