Re: [Qemu-devel] [PATCH] coroutine: add ./configure --disable-coroutine-pool

[Stefan Weil <sw@weilnetz.de>]

Am 11.09.2013 16:42, schrieb Stefan Hajnoczi:
> The 'gthread' coroutine backend was written before the freelist (aka
> pool) existed in qemu-coroutine.c.
>
> This means that every thread is expected to exit when its coroutine
> terminates.  It is not possible to reuse threads from a pool.
>
> This patch automatically disables the pool when 'gthread' is used.  This
> allows the 'gthread' backend to work again (for example,
> tests/test-coroutine completes successfully instead of hanging).
>
> I considered implementing thread reuse but I don't want quirks like CPU
> affinity differences due to coroutine threads being recycled.  The
> 'gthread' backend is a reference backend and it's therefore okay to skip
> the pool optimization.
>
> Note this patch also makes it easy to toggle the pool for benchmarking
> purposes:
>
>   ./configure --with-coroutine-backend=ucontext \
>               --disable-coroutine-pool
>
> Reported-by: Gabriel Kerneis <gabriel@kerneis.info>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
>  configure        | 24 ++++++++++++++++++++++++
>  qemu-coroutine.c | 34 +++++++++++++++++++---------------
>  2 files changed, 43 insertions(+), 15 deletions(-)
>

This patch is important for QEMU 1.5 as well, but needs some
modifications there.
A recent bug report for MinGW shows that the win32 coroutine needs it, too.

Stefan, could you please prepare a patch for stable-1.5?

Regards
Stefan W.