Re: [patch 00/13] Syslets, "Threadlets", generic AIO support, v3

Evgeniy Polyakov
2007-02-27T10:43:52Z

On Tue, Feb 27, 2007 at 07:24:19AM +0100, Ingo Molnar (mingo@elte.hu) wrote:
>
> * Evgeniy Polyakov <johnpol@2ka.mipt.ru> wrote:
>
> > On Mon, Feb 26, 2007 at 01:51:23PM +0100, Ingo Molnar (mingo@elte.hu) wrote:
> > >
> > > * Evgeniy Polyakov <johnpol@2ka.mipt.ru> wrote:
> > >
> > > > Even having main dispatcher as epoll/kevent loop, the _whole_
> > > > threadlet model is absolutely micro-thread in nature and not state
> > > > machine/event.
> > >
> > > Evgeniy, i'm not sure how many different ways to tell this to you, but
> > > you are not listening, you are not learning and you are still not
> > > getting it at all.
> > >
> > > The scheduler /IS/ a generic work/event queue. And it's pretty damn
> > > fast. No amount of badmouthing will change that basic fact. Not exactly
> > > as fast as a special-purpose queueing system (for all the reasons i
> > > outlined to you, and which you ignored), but it gets pretty damn close
> > > even for the web workload /you/ identified, and offers a user-space
> > > programming model that is about 1000 times more useful than
> > > state-machines.
> >
> > Meanwhile on practiceal side:
> > via epia kevent/epoll/threadlet:
> >
> > client: ab -c500 -n5000 $url
> >
> > kevent: 849.72
> > epoll: 538.16
> > threadlet:
> > gcc ./evserver_epoll_threadlet.c -o ./evserver_epoll_threadlet
> > In file included from ./evserver_epoll_threadlet.c:30:
> > ./threadlet.h: In function ‘threadlet_exec’:
> > ./threadlet.h:46: error: can't find a register in class ‘GENERAL_REGS’
> > while reloading ‘asm’
> >
> > That particular asm optimization fails to compile.
>
> it's not really an asm optimization but an API glue. I'm using:
>
> gcc -O2 -g -Wall -o evserver_epoll_threadlet evserver_epoll_threadlet.c -fomit-frame-pointer
>
> does that work for you?

Yes, -fomit-frame-point make the deal.

In average, threadlet runs as fast as epoll.
Just because there are _no_ rescheduling in that case.

I added a printk into __async_schedule() and started
ab -c7000 -n20000 http://192.168.4.80/
against slow via epia, and got only one of them.
Client is latest
../async-test-v4/evserver_epoll_threadlet

Btw, I need to admit, that I have totally broken kevent tree there - it
does not work on that machine on higher loads, so I'm investigating that
problem now.

> Ingo

--
Evgeniy Polyakov