newbuf, nbufkv, nbufbs

d_elbracht d_elbracht at
Sun Oct 14 07:42:13 PDT 2007

We have 2 machines involved with this problem.

machine1, SMP, i386, 4 GB RAM was recently upgraded from 5.4 to 6.2 cvsup'ed

a partition of about 2.5 TB (gstripe -s 1048576) was newfs'ed with blocksize
of 65536 and fragsize of 8192 
On 5.4, this was running for months with no problem.

On 6.2 after a few hours of high thruput (network tx and rx 400-500 Mbit
each), it became unresponsible with top showing a lot of processes with
waitmessage newbuf.

So, reset, fsck etc and it run again, only after a few hours, it became
unresponsible again, showing processes with nbufkv and nbufbs

this time, I did newfs with blocksize of 32768 and fragsize of 4096 and it's
running. Thruput is decreased to 300-400 Mbit

Note, it did NEVER show the problem on 5.4

machine2, SMP, amd64, 16 GB RAM, 6.2 cvsup'ed 2007-10-09
20 partitions involving 51 disks, all gstripe -s 1048576, newfs -b 65536 -f
1 partion of 12 GB, (da3s1a) newfs -b 65536 -f 8192
after a few hours, top shows newbuf and the machine is unresponsible.
tps on da3s1a is > 500, the others are < 100
I did newfs -b 8192 -f 1024 /dev/da3s1a and it's running without the problem

The problem seems to have to do with -b 65536 and lot's of IOPS ond 6.2

Any clue ? e.g. increase BKVASIZE to 131072 and kern.nbuf to 32768 ?



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