Subject: Re: kern/8217: periodic pciide pauses?
To: None <firstname.lastname@example.org>
From: Bill Sommerfeld <email@example.com>
Date: 08/17/1999 18:54:04
I'm beginning to suspect a "high kernel" problem (not
Some experimental observations:
The pauses appear to correlate well with sync(2) invocations and
writing of dirty data to disk.
- pauses are not obvious for me when I kill update
- when i replace update with a:
echo -n x; sync
pauses corrlate with the printing of "x"'s
- pauses are significantly less severe when you turn off atime
updates (with mount -u -o noatime <filesystem>)
I suspect that's what going on here is a scaling problem; systems are
dirtying data at ever-faster memory speeds, and then flushing it at
disk speeds only every 30s, leading to a significant pause..
It's not immediately clear what's causing the other processes to block
during the sync; ffs_update is one likely place (for instance, if the
bread() call it makes misses in the cache..).