From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49532) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bJxHW-00074h-KL for qemu-devel@nongnu.org; Mon, 04 Jul 2016 02:22:59 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bJxHR-0007Mv-Km for qemu-devel@nongnu.org; Mon, 04 Jul 2016 02:22:58 -0400 Received: from mx-v6.kamp.de ([2a02:248:0:51::16]:40254 helo=mx01.kamp.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bJxHR-0007Mp-BQ for qemu-devel@nongnu.org; Mon, 04 Jul 2016 02:22:53 -0400 References: <1467272240-32123-1-git-send-email-pl@kamp.de> <1467272240-32123-7-git-send-email-pl@kamp.de> From: Peter Lieven Message-ID: <577A00B1.3010508@kamp.de> Date: Mon, 4 Jul 2016 08:22:41 +0200 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 6/6] coroutine: reduce stack size to 64kB List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Richard Henderson , qemu-devel@nongnu.org Cc: kwolf@redhat.com, peter.maydell@linaro.org, mst@redhat.com, dgilbert@redhat.com, mreitz@redhat.com, pbonzini@redhat.com Am 01.07.2016 um 23:13 schrieb 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 >> --- >> 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). for x86_64 it seems to be 16k. I would not mind to adjust the stack size either in qemu_alloc_stack or change the macro for the coroutine stack size into a function returning MAX(1 << 16, sysconf(_SC_THREAD_STACK_MIN)). Peter