Re: [Qemu-devel] [PATCH 6/6] coroutine: reduce stack size to 64kB

[Richard Henderson]

On 06/30/2016 12:37 AM, Peter Lieven wrote:
> evaluation with the recently introduced maximum stack usage monitoring revealed
> that the actual used stack size was never above 4kB so allocating 1MB stack
> for each coroutine is a lot of wasted memory. So reduce the stack size to
> 64kB which should still give enough head room.
>
> Signed-off-by: Peter Lieven <address@hidden>
> ---
>  include/qemu/coroutine_int.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/qemu/coroutine_int.h b/include/qemu/coroutine_int.h
> index eac323a..f84d777 100644
> --- a/include/qemu/coroutine_int.h
> +++ b/include/qemu/coroutine_int.h
> @@ -28,7 +28,7 @@
>  #include "qemu/queue.h"
>  #include "qemu/coroutine.h"
>
> -#define COROUTINE_STACK_SIZE (1 << 20)
> +#define COROUTINE_STACK_SIZE (1 << 16)
>
>  typedef enum {
>      COROUTINE_YIELD = 1,

Ought we check that this is not smaller than

    sysconf(_SC_THREAD_STACK_MIN)

which (for glibc at least), is 192k for ia64, 128k for aarch64, mips and tile 
(though why it is quite so high in those later cases I don't know).


r~