From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51226) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1c4pXP-00087V-ER for qemu-devel@nongnu.org; Thu, 10 Nov 2016 08:37:10 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1c4pXM-0001eI-Cr for qemu-devel@nongnu.org; Thu, 10 Nov 2016 08:37:07 -0500 Received: from mail-wm0-x22d.google.com ([2a00:1450:400c:c09::22d]:36874) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1c4pXL-0001cF-Uv for qemu-devel@nongnu.org; Thu, 10 Nov 2016 08:37:04 -0500 Received: by mail-wm0-x22d.google.com with SMTP id t79so31985066wmt.0 for ; Thu, 10 Nov 2016 05:37:03 -0800 (PST) References: <1473847013-20191-1-git-send-email-pbonzini@redhat.com> <87k2cb8st5.fsf@linaro.org> From: Alex =?utf-8?Q?Benn=C3=A9e?= In-reply-to: Date: Thu, 10 Nov 2016 13:37:00 +0000 Message-ID: <87h97f8nib.fsf@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] [PATCH 0/3] target-arm: cache tbflags in CPUARMState List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: qemu-devel@nongnu.org Paolo Bonzini writes: > On 10/11/2016 12:42, Alex Bennée wrote: >> >> Paolo Bonzini writes: >> >>> Computing TranslationBlock flags is pretty expensive on ARM, especially >>> 32-bit. Because tbflags are computed on every tb lookup, it is not >>> unlikely to see cpu_get_tb_cpu_state close to the top of the profile >>> now that QHT makes the hash table much more efficient. >>> >>> However, most tbflags only change when the EL is switched or after >>> MSR instructions. Based on this observation, this series caches these >>> tbflags in CPUARMState, resulting in a 10-15% speedup on 32-bit code. >> >> Hi, >> >> I'm starting to clear out my review queue but I notice these now longer >> apply cleanly to master. Where you going to re-issue the series once >> you'd addressed Peter's concerns? > > Yes, I didn't want to send them two days before soft freeze and Peter's > vacation. :) Cool. Well I'll happily look at it while he's away as I think I need to learn more about the flag mechanism anyway. Unless there are any regressions that have come up during soft-freeze that I need to look at? -- Alex Bennée