From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60728) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bwT0x-00064h-18 for qemu-devel@nongnu.org; Tue, 18 Oct 2016 07:57:04 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bwT0t-0004mt-S8 for qemu-devel@nongnu.org; Tue, 18 Oct 2016 07:57:03 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:38510) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1bwT0t-0004mI-Kt for qemu-devel@nongnu.org; Tue, 18 Oct 2016 07:56:59 -0400 Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.17/8.16.0.17) with SMTP id u9IBsnnx089642 for ; Tue, 18 Oct 2016 07:56:57 -0400 Received: from e06smtp10.uk.ibm.com (e06smtp10.uk.ibm.com [195.75.94.106]) by mx0a-001b2d01.pphosted.com with ESMTP id 265jtt1kdm-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Tue, 18 Oct 2016 07:56:56 -0400 Received: from localhost by e06smtp10.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 18 Oct 2016 12:56:54 +0100 Received: from b06cxnps4076.portsmouth.uk.ibm.com (d06relay13.portsmouth.uk.ibm.com [9.149.109.198]) by d06dlp01.portsmouth.uk.ibm.com (Postfix) with ESMTP id B39BE17D805D for ; Tue, 18 Oct 2016 12:59:03 +0100 (BST) Received: from d06av06.portsmouth.uk.ibm.com (d06av06.portsmouth.uk.ibm.com [9.149.37.217]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u9IBuqdc2228722 for ; Tue, 18 Oct 2016 11:56:52 GMT Received: from d06av06.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av06.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u9IBupXB009804 for ; Tue, 18 Oct 2016 07:56:52 -0400 Date: Tue, 18 Oct 2016 13:56:48 +0200 From: Greg Kurz In-Reply-To: <20161018130007.623f1fa8@nial.brq.redhat.com> References: <1475541180-16363-1-git-send-email-aik@ozlabs.ru> <9a52afb0-79d1-0b53-a271-516724b766a6@ozlabs.ru> <20161018130007.623f1fa8@nial.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Message-Id: <20161018135648.3c319b41@bahia> Subject: Re: [Qemu-devel] [PATCH qemu] sysemu: support up to 1024 vCPUs List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Igor Mammedov Cc: Alexey Kardashevskiy , qemu-devel@nongnu.org, David Gibson On Tue, 18 Oct 2016 13:00:07 +0200 Igor Mammedov wrote: > On Tue, 11 Oct 2016 09:19:10 +1100 > Alexey Kardashevskiy wrote: > > > Ping, anyone? > I have a similar patch > http://patchwork.ozlabs.org/patch/681709/ > which bumps limit to 288 and does a little bit more > so it wouldn't affect current users. > Heh the bumping to 1024 was kinda arbitrary but 288 would be an improvement anyway. FYI, only Alpine class servers would benefit from that since they have 320 threads, even if they're not officially supported to run a KVM based hypervisor (biggest supported model is Tuleta with 192 threads). BTW, the afore mentioned patch keeps the current 255 limit for pseries machine types. I guess David's answer means that the hw/ppc/spapr.c hunk can be safely dropped. > After that's merged, I plan to get rid of this limit and > make that part of numa parsing code dynamic so that it > wouldn't impose such limit/any limits on target code. > > > > > > > On 04/10/16 11:33, Alexey Kardashevskiy wrote: > > > From: Greg Kurz > > > > > > Some systems can already provide more than 255 hardware threads. > > > > > > Bumping the QEMU limit to 1024 seems reasonable: > > > - it has no visible overhead in top; > > > - the limit itself has no effect on hot paths. > > > > > > Signed-off-by: Greg Kurz > > > Signed-off-by: Alexey Kardashevskiy > > > --- > > > include/sysemu/sysemu.h | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h > > > index ef2c50b..2ec0bd8 100644 > > > --- a/include/sysemu/sysemu.h > > > +++ b/include/sysemu/sysemu.h > > > @@ -173,7 +173,7 @@ extern int mem_prealloc; > > > * > > > * Note that cpu->get_arch_id() may be larger than MAX_CPUMASK_BITS. > > > */ > > > -#define MAX_CPUMASK_BITS 255 > > > +#define MAX_CPUMASK_BITS 1024 > > > > > > #define MAX_OPTION_ROMS 16 > > > typedef struct QEMUOptionRom { > > > > > > > >