From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4D176C10F1A for ; Tue, 7 May 2024 10:01:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:From:References:Cc:To: Subject:MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=hBiCfq3jyn1AQlazd+pu/4Ym9RRjhlxvJW7lHJNdPTE=; b=eyPDgkSCTlEtEd bfmlrIfZZHxYHeZGFKQx259MpJAU1DmF3JaHb3yLgzk4tB2UsxQOddNDkBd8++Bh1F4P2NE6CtGof AJlCJWY1oDWbsKLW9TvyWh5G/64PeAsRRuc0oAvg8JTjvwgpwjjVfLekqXsvYulmg1kIwuvi/IgqV +K5rJGDGzLyI1U8LxGU4lSZmKZ4kaihcNtsopztV9U3dYmAOJZVFeRQHIkOiM1yhvCK2rAHnw6q2G NhWrsbKICieqTH7UmB9cuABlchVoz3OhhqPbx4FZ6xe/e9qqrAV2mzwBrYqckICH6jptaH4P8oVLr 5KLU038WfoJckoL3a/Uw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1s4HdM-0000000ARn9-28Rm; Tue, 07 May 2024 10:01:16 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1s4HdJ-0000000ARlM-04qz for linux-arm-kernel@lists.infradead.org; Tue, 07 May 2024 10:01:14 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 0F2D51063; Tue, 7 May 2024 03:01:38 -0700 (PDT) Received: from [192.168.1.100] (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 51D093F587; Tue, 7 May 2024 03:01:09 -0700 (PDT) Message-ID: <4ab27bea-ac94-48c3-827c-9f2eddcdd50a@arm.com> Date: Tue, 7 May 2024 11:01:07 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 00/17] coresight: Use per-sink trace ID maps for Perf sessions To: Arnaldo Carvalho de Melo Cc: linux-perf-users@vger.kernel.org, gankulkarni@os.amperecomputing.com, scclevenger@os.amperecomputing.com, coresight@lists.linaro.org, suzuki.poulose@arm.com, mike.leach@linaro.org, Alexander Shishkin , Maxime Coquelin , Alexandre Torgue , Peter Zijlstra , Ingo Molnar , Namhyung Kim , Mark Rutland , Jiri Olsa , Ian Rogers , Adrian Hunter , John Garry , Will Deacon , Leo Yan , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com References: <20240429152207.479221-1-james.clark@arm.com> Content-Language: en-US From: James Clark In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240507_030113_143223_75604B2A X-CRM114-Status: GOOD ( 20.63 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 03/05/2024 21:23, Arnaldo Carvalho de Melo wrote: > On Mon, Apr 29, 2024 at 04:21:45PM +0100, James Clark wrote: >> This will allow sessions with more than CORESIGHT_TRACE_IDS_MAX ETMs >> as long as there are fewer than that many ETMs connected to each sink. >> >> Each sink owns its own trace ID map, and any Perf session connecting to >> that sink will allocate from it, even if the sink is currently in use by >> other users. This is similar to the existing behavior where the dynamic >> trace IDs are constant as long as there is any concurrent Perf session >> active. It's not completely optimal because slightly more IDs will be >> used than necessary, but the optimal solution involves tracking the PIDs >> of each session and allocating ID maps based on the session owner. This >> is difficult to do with the combination of per-thread and per-cpu modes >> and some scheduling issues. The complexity of this isn't likely to worth >> it because even with multiple users they'd just see a difference in the >> ordering of ID allocations rather than hitting any limits (unless the >> hardware does have too many ETMs connected to one sink). >> >> Per-thread mode works but only until there are any overlapping IDs, at >> which point Perf will error out. Both per-thread mode and sysfs mode are >> left to future changes, but both can be added on top of this initial >> implementation and only sysfs mode requires further driver changes. >> >> The HW_ID version field hasn't been bumped in order to not break Perf >> which already has an error condition for other values of that field. >> Instead a new minor version has been added which signifies that there >> are new fields but the old fields are backwards compatible. > > I guess I can pick the tooling part now, right? Further reviewing would > be nice tho. > > - Arnaldo Is it ok if we wait for the driver changes to be merged first? There might some review comments which need a format change to the packets and then a re-write of the tool changes. You could take 1 and 2 though because they're unrelated. Thanks James _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel