Messages in this thread | | | Date | Tue, 4 Nov 2003 11:36:55 -0800 (PST) | From | Linus Torvalds <> | Subject | Re: ext3 performance inconsistencies, 2.4/2.6 |
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On Tue, 4 Nov 2003, Paul Venezia wrote: > > I've been running bonnie++ filesystems testing on an IBM x335 server > recently. This box uses the MPT RAID controller, but I've disabled the > RAID and am addressing the disks individually. I'm getting wildly > different results between 2.4.20-20-9 (RedHat mod), 2.4.22 (stock), and > 2.6.0-test9.
Interesting. The 2.4.22 sequential "per char" results are totally out of line with anything else.
The thing is, the overhead for the per-char stuff really should be almost all in user space unless I'm mistaken. It's just using getch/putch, no?
Which makes me suspect that either the libc does something different depending on kernel version, _or_ 2.4.22 returns a different st_blksize thing, causing stdio to use a different blocking size.
Have you tried stracing the "per char" parts of the benchmark to see what the system call patterns are? That should show both effects.
Linus
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