On 05/03/2015 15:16, Robert Schulze wrote:
Hi,
These values look totally reasonable in terms a d/s.
How does this compare to the none gmirror case?
Its barely measurable, but in this case I can start a loop directly
after unlink with very small interval. The only measurement with
non-null values is:
dT: 0.205s w: 0.200s filter: ada
L(q) ops/s r/s kBps ms/r w/s kBps ms/w d/s kBps ms/d %busy Name
0 0 0 0 0.0 0 0 0.0 0 0 0.0 0.0 ada0
0 51537 5 156 2.4 0 0 0.0 51532 1649018 3.8 18.2 ada1
thats all. It takes not even half a second to push the DELETE ops to the
SSD in case of non-gmirrored UFS. Again, with a 2 GB file.
That is a high rate, but not inconceivable.
Compile a version of the kernel with this change reverted.
Details of the change can be seen here.
https://svnweb.freebsd.org/base?view=revision&revision=268816
done, but it did not change behaviour.
Thanks, I think we need to do some dtrace instrumentation, to get a
better picture of what's happening.
If you pick a smaller file, say 10MB what does the following dtrace
script report for the single disk no gmirror and for a single disk
gmirror (if thats possible)
#!/usr/sbin/dtrace -s
#pragma D option quiet
enum bio_type {
BIO_DELETE = 0x04
};
fbt::adastrategy:entry
/((struct bio *)arg0)->bio_cmd == BIO_DELETE/
{
bp = (struct bio *)arg0;
periph = (struct cam_periph *)bp->bio_disk->d_drv1;
softc = (struct ada_softc *)periph->softc;
printf("%Y ada%d bcount: %d, offset: %d\n", walltimestamp,
periph->unit_number, bp->bio_bcount, bp->bio_pblkno);
}
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