Re: high load, no bottleneck

[christos%astron.com@localhost (Christos Zoulas)]

In article <1l9czcn.y6kr35aruvzvM%manu%netbsd.org@localhost>,
Emmanuel Dreyfus <manu%netbsd.org@localhost> wrote:
>Emmanuel Dreyfus <manu%netbsd.org@localhost> wrote:
>
>> db{0}> show vnode c5a24b08
>> OBJECT 0xc5a24b08: locked=0, pgops=0xc0b185a8, npages=1720, refs=16
>> 
>> VNODE flags 0x4030<MPSAFE,LOCKSWORK,ONWORKLST>
>> mp 0xc4a14000 numoutput 0 size 0x6f0000 writesize 0x6f0000
>> data 0xc5a25d74 writecount 0 holdcnt 2
>> tag VT_UFS(1) type VREG(1) mount 0xc4a14000 typedata 0xc4fe5480
>> v_lock 0xc5a24bac
>
>While many threads are waiting, another nfsd thread holds the lock with
>this backtrace:
>turnstile_block
>rw_vector_enter
>wapbl_begin
>ffs_write
>VOP_WRITE
>nfsrv_write
>nfssvc_nfsd
>sys_nfssvc
>syscall
>
>I understand it is waiting for another process to complete I/O before
>passing the entering rwlock in wapbl_begin
>
>I have a first-class suspect with this other nfsd thread which is
>engaged in I/O:
>sleepq_block
>wdc_exec_command
>wd_flushcache
>wdioctl
>bdev_ioctl
>spec_ioctl
>VOP_IOCTL
>rf_sync_component_caches
>raidioctl
>bdev_ioctl
>spec_ioctl
>VOP_IOCTL
>wapbl_cache_sync
>
>Is it a nasty interraction between RAIDframe, NFS and WAPBL?

My suggestion is to try:

    sysctl -w vfs.wapbl.flush_disk_cache=0

for now...

christos