From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [103.22.144.67]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 721E31A0BE3 for ; Fri, 30 Oct 2015 10:40:57 +1100 (AEDT) Received: from e34.co.us.ibm.com (e34.co.us.ibm.com [32.97.110.152]) (using TLSv1 with cipher CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id B6808140E6F for ; Fri, 30 Oct 2015 10:40:56 +1100 (AEDT) Received: from localhost by e34.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 29 Oct 2015 17:40:54 -0600 Received: from b03cxnp08027.gho.boulder.ibm.com (b03cxnp08027.gho.boulder.ibm.com [9.17.130.19]) by d03dlp03.boulder.ibm.com (Postfix) with ESMTP id AD67619D803F for ; Thu, 29 Oct 2015 17:29:01 -0600 (MDT) Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by b03cxnp08027.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id t9TNeqqu9634208 for ; Thu, 29 Oct 2015 16:40:52 -0700 Received: from d03av02.boulder.ibm.com (localhost [127.0.0.1]) by d03av02.boulder.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id t9TNepgF003140 for ; Thu, 29 Oct 2015 17:40:51 -0600 From: Suresh Warrier To: linuxppc-dev@ozlabs.org Cc: warrier@linux.vnet.ibm.com, paulus@samba.org, mpe@ellerman.id.au Subject: [PATCH 0/2] Increase number of supported IPI messages Date: Thu, 29 Oct 2015 18:40:43 -0500 Message-Id: <1446162045-26496-1-git-send-email-warrier@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , When a H_IPI hypercall is made, we often need to switch to the host to poke the VCPU to which the virtual IPI is targeted. This is because we cannot do a thread wake-up in real mode in the guest. Peformance tests have shown that this is impacting several different workloads - from MongoDB to small message networking. One solution is to hand off this job of waking the VCPU to a CPU that is running in the host by sending it a message through the IPI mechanism from the guest. Currently, we only support 4 IPI messages and all 4 are already used for other purposes. This patch set increases the number of supported IPI messages to 8. It also provides the code to send an IPI from KVM real-mode since the existing cause_ipi functions cannot be executed in real-mode. There is an associated patch set for "KVM: PPC: Book3S HV" that implements the actual solution to avoid the switch to host to do the VCPU wakeup. Suresh Warrier (2): powerpc/smp: Support more IPI messages powerpc/smp: Add smp_muxed_ipi_rm_message_pass arch/powerpc/include/asm/smp.h | 4 ++++ arch/powerpc/kernel/smp.c | 38 ++++++++++++++++++++++++++++++++++---- 2 files changed, 38 insertions(+), 4 deletions(-) -- 1.8.3.4