Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1946102AbbGQNsW (ORCPT ); Fri, 17 Jul 2015 09:48:22 -0400 Received: from m12-17.163.com ([220.181.12.17]:45418 "EHLO m12-17.163.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757992AbbGQNsV convert rfc822-to-8bit (ORCPT ); Fri, 17 Jul 2015 09:48:21 -0400 Content-Type: text/plain; charset=gb2312 Mime-Version: 1.0 (1.0) Subject: Re: [RFC PATCH 5/6] bpf: Implement function bpf_read_pmu() that get the selected hardware PMU conuter From: pi3orama X-Mailer: iPhone Mail (12H143) In-Reply-To: <20150717132657.GM19282@twins.programming.kicks-ass.net> Date: Fri, 17 Jul 2015 21:45:36 +0800 Cc: "Wangnan (F)" , kaixu xia , "ast@plumgrid.com" , "davem@davemloft.net" , "acme@kernel.org" , "mingo@redhat.com" , "masami.hiramatsu.pt@hitachi.com" , "jolsa@kernel.org" , "linux-kernel@vger.kernel.org" , "hekuang@huawei.com" Content-Transfer-Encoding: 8BIT Message-Id: <13432865-8DCB-4100-95C7-DC59D4968B9A@163.com> References: <55A8E703.70306@huawei.com> <20150717113924.GD19282@twins.programming.kicks-ass.net> <55A8EABE.1060308@huawei.com> <20150717115505.GF19282@twins.programming.kicks-ass.net> <20150717115615.GA18673@twins.programming.kicks-ass.net> <55A8EE83.3000708@huawei.com> <20150717121836.GH19282@twins.programming.kicks-ass.net> <55A8F4BF.3020902@huawei.com> <20150717124538.GI19282@twins.programming.kicks-ass.net> <45F8BB22-F978-4671-BAD0-6DE3643EA04C@163.com> <20150717132657.GM19282@twins.programming.kicks-ass.net> To: Peter Zijlstra X-CM-TRANSID: EcCowACnOW3_BqlViAdZAA--.17931S2 X-Coremail-Antispam: 1Uf129KBjvdXoW7Wr4DKrWDAF18Jr1DWw48Zwb_yoWfXwb_Xr 9I9wsrCw1UWwnxXFsFq343ArZ7Xan8WryjvrWrW34Ig3y8ZF95GFn5GrZava43JrWUW3Zr Gr4aq34fJ34a9jkaLaAFLSUrUUUUUb8apTn2vfkv8UJUUUU8Yxn0WfASr-VFAUDa7-sFnT 9fnUUvcSsGvfC2KfnxnUUI43ZEXa7IU81lk3UUUUU== X-Originating-IP: [210.73.4.168] X-CM-SenderInfo: lslt02xdpdqiywtou0bp/xtbBaQM6QFD--K4OHAAAs- Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1130 Lines: 31 ?????ҵ? iPhone > ?? 2015??7??17?գ?????9:26??Peter Zijlstra д???? > > On Fri, Jul 17, 2015 at 08:57:00PM +0800, pi3orama wrote: >>>> But what if we really want cross-cpu PMU accessing? Impossible? >>> >>> Under the assumption that the eBPF program is called from tracing, and >>> therefore from any context (task, softirq, irq and nmi), yes impossible. >>> >>> You cannot do (synchronous) IPIs from either IRQ context or with IRQs >>> disabled. And both are valid trace contexts. >> >> What about software perf event? For example, tracepoints? > > Some of them, tracepoints would work. So you could exempt > TYPE_TRACEPOINT, but I would suggest starting as constrained as possible > and relaxing when we really need/want. > > Thanks to your advise. We will follow them in v2. Do you have further comment on other part of this patch set? Thank you. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/