On 4/13/13 10:42 AM, weijin wrote:
On 04/13/2013 07:27 AM, James Peach wrote:
On Apr 11, 2013, at 7:25 PM, weijin <weilogs...@126.com> wrote:
after changed to Linux Native AIO, the AIO callback happened in the same
thread, that means all subsequent operations of vol init will be also
happened in only one thread.
Why is this? Is it due to the way your change works or the way Linux AIO
works?
yes, If enable_native_aio, which thread submit, which handle callbacks
So this implies that a system with only one or a couple of disks, all AIO
happens on one (or two) threads? That seems like a pretty common use case,
and performance could potentially suffer.
Maybe we should have a way to combine this with "AIO callback" threads, such
that I can have these callbacks on a thread that's not doubling up as
Net-thread (ET_TASK) ? As example, it'd be a pretty normal setup to have one
cache disk, and 2 net-threads, running on the same box as the "origin". In
this setup, having a third thread for native AIO seems like a better solution?
But the previous aio can callback in any ET_CALL thread, so in most case
the vol init operations can spread to many thread.
So does that mean that you only have 1 thread handling AIO for each disk?
What is the performance profile of that?
the vol::init will first read the dirs, then do the recover logics. the
recover logics is complicate and may read data more than one time. We may
have many vols and I will Vol::init (recover logics) can be done paralleled.
Hmmm, on my prod box, there's only one volume...
Cheers,
-- Leif
