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? -- | Jeremy Chadwick j...@parodius.com | | Parodius Networking http://www.parodius.com/ | | UNIX Systems Administrator Mountain View, CA, USA | | Making life hard for others since 1977. PGP 4BD6C0CB | _______________________________________________ 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"
