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 8E71BC54EE9 for ; Thu, 22 Sep 2022 13:08:10 +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=Y7LItqsboJd/1TDCGWcVAMrKTYa1HVm8YZfmhuKJ/fA=; b=2OYh5EK1e4K40S cikoDFWrWi5lHyi1fNcbRad5L4kAT/HC0mP/R0Flw3eJlC6eUer873QQ6XMTz3FZbgZZEPjWvGHdr jAovCV64HdiDEomHt7x3SVSlEhHkC3QxKQJ4daWb8Q+CaeJ1KXFItwrv68WpxNkiEymtwT9p0Hzhw rnuD41s7X4hkU8eMgQfkUxSdKVoxDV0HlBy8IYhSL/HmJFqbp/XA7ghjEUlYHAX0V6QSebvHm8O8z 6m85OmW1au4RG9P2NHJ8Uv8e2tTZUX1Fhc36E6gmgtkdFoJPUShyw1/3gWaRXfbTblL/0DMVkPSgE i7JnBwKbmZxeM4qk+CGw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1obLv3-00FYTy-6F; Thu, 22 Sep 2022 13:07:09 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1obLv0-00FYPM-EG for linux-arm-kernel@lists.infradead.org; Thu, 22 Sep 2022 13:07:08 +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 29F8A1595; Thu, 22 Sep 2022 06:06:52 -0700 (PDT) Received: from [10.57.1.91] (unknown [10.57.1.91]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0ACD83F73B; Thu, 22 Sep 2022 06:06:43 -0700 (PDT) Message-ID: <489f42fc-2ec1-510b-6f3f-017ee10ee7d2@arm.com> Date: Thu, 22 Sep 2022 14:06:42 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH 0/1] arm64: defconfig: Add Coresight as module Content-Language: en-US To: Catalin Marinas Cc: coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, suzuki.poulose@arm.com, mathieu.poirier@linaro.org, mike.leach@linaro.org, leo.yan@linaro.org, broonie@kernel.org, linux-kernel@vger.kernel.org, Will Deacon , Mark Rutland References: <20220921140535.152627-1-james.clark@arm.com> From: James Clark In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220922_060706_573478_39299933 X-CRM114-Status: GOOD ( 16.77 ) 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 22/09/2022 11:52, Catalin Marinas wrote: > On Thu, Sep 22, 2022 at 10:34:45AM +0100, James Clark wrote: >> On 21/09/2022 16:08, Catalin Marinas wrote: >>> 2. Always on CONFIG_PID_IN_CONTEXTIDR (we might as well remove the >>> Kconfig entry). This would write the root pid namespace value >>> (task_pid_nr()). >> >> If we're not worried about the overhead after all, this would be the >> easiest solution. And then SPE or Coresight already decide whether they >> want to use the value or not, so no further changes are needed. >> >> From Leo's patch there is a table that shows a 1% overhead with it >> enabled permanently, and I've heard a figure like that mentioned before. >> So I could also resurrect that patch to use static keys? Although it's a >> bit more complicated, that would be my preference. And then we can have >> that mode always on. > > I don't think we should bother with static keys, just always enable it > but try to reduce/group the ISBs from all the functions called on the > __switch_to() path. We may actually get a speed-up. > Ok thanks I will take a look at this _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel