From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54126) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ch7vP-0006aP-P6 for qemu-devel@nongnu.org; Thu, 23 Feb 2017 23:56:12 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ch7vM-0007wE-ON for qemu-devel@nongnu.org; Thu, 23 Feb 2017 23:56:11 -0500 From: Alexey Kardashevskiy Date: Fri, 24 Feb 2017 15:55:31 +1100 Message-Id: <20170224045531.7026-1-aik@ozlabs.ru> Subject: [Qemu-devel] [PATCH qemu] sysemu: support up to 1024 vCPUs List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Alexey Kardashevskiy , qemu-ppc@nongnu.org, David Gibson , Greg Kurz , Greg Kurz 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. Cc: Greg Kurz Signed-off-by: Alexey Kardashevskiy --- With ulimit -u/-n bumped (nproc and nofile), I was able to boot a guest with 1024 CPUs, both with threads=1 and threads=8. It takes time though - 3:15 to get to the guest shell but it is probably expected on 160-threads machine. --- hw/ppc/spapr.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c index e465d7ac98..46b81a625d 100644 --- a/hw/ppc/spapr.c +++ b/hw/ppc/spapr.c @@ -2712,7 +2712,7 @@ static void spapr_machine_class_init(ObjectClass *oc, void *data) mc->init = ppc_spapr_init; mc->reset = ppc_spapr_reset; mc->block_default_type = IF_SCSI; - mc->max_cpus = 255; + mc->max_cpus = 1024; mc->no_parallel = 1; mc->default_boot_order = ""; mc->default_ram_size = 512 * M_BYTE; -- 2.11.0