Re: high load, no bottleneck

[manu%netbsd.org@localhost (Emmanuel Dreyfus)]

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?



-- 
Emmanuel Dreyfus
http://hcpnet.free.fr/pubz
manu%netbsd.org@localhost