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 894F9C3DA4A for ; Mon, 19 Aug 2024 15:01:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type: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=30GBWgFOrBQW/dTgWuNaD4jlzkuo8NfhD/jYmciqIwM=; b=SggRtCFtrQNAO83uk6LfWyrSLG laZTvDBFLRsYCWNLJgBuooa0nQWbMxXRHrv2KMeGldPlGkFul4OV4Uo2nfC4sQ3whsgFcqlx7JsAj iFMmiPDuDIqtDEYJDq5Gg2rxbwLILeG2blivSmc+1Wy2wxgZEXVx/qGHnazKbkMulAShvgXttBnOd dlsTZN8i+VnIcHSllhtzf2rfMRePsrCKASlYZ0savAe2sjmezKSJ3QKXVIbv4IwDcW8wXaQspN4F0 7A89a6MlA8BBwt8/HUL0SpREmpognT/692FE2jxF3Q7Plv1KM1a+LkSxIQQwKq7L/RJDxsSoh1ysB tXMMo29A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sg3sP-00000001rPY-0cgV; Mon, 19 Aug 2024 15:00:57 +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 1sg3rd-00000001r9h-1Tw2 for linux-arm-kernel@lists.infradead.org; Mon, 19 Aug 2024 15:00:10 +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 430B1339; Mon, 19 Aug 2024 08:00:34 -0700 (PDT) Received: from [10.1.196.40] (e121345-lin.cambridge.arm.com [10.1.196.40]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 75AA73F66E; Mon, 19 Aug 2024 08:00:07 -0700 (PDT) Message-ID: <22b69400-af16-4e78-8f72-c10564d7cc6c@arm.com> Date: Mon, 19 Aug 2024 16:00:06 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 3/8] perf/arm-cmn: Ensure dtm_idx is big enough To: Mark Rutland Cc: will@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, ilkka@os.amperecomputing.com References: From: Robin Murphy Content-Language: en-GB In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240819_080009_519207_9814F45A X-CRM114-Status: GOOD ( 18.20 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 16/08/2024 11:14 am, Mark Rutland wrote: > On Fri, Aug 09, 2024 at 08:15:42PM +0100, Robin Murphy wrote: >> While CMN_MAX_DIMENSION was bumped to 12 for CMN-650, that only supports >> up to a 10x10 mesh, so bumping dtm_idx to 256 bits at the time worked >> out OK in practice. However CMN-700 did finally support up to 144 XPs, >> and thus needs a worst-case 288 bits of dtm_idx for an aggregated XP >> event on a maxed-out config. Oops. >> >> Fixes: 23760a014417 ("perf/arm-cmn: Add CMN-700 support") >> Signed-off-by: Robin Murphy >> --- >> drivers/perf/arm-cmn.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c >> index 0e2e12e2f4fb..c9a2b21a7aec 100644 >> --- a/drivers/perf/arm-cmn.c >> +++ b/drivers/perf/arm-cmn.c >> @@ -563,7 +563,7 @@ static void arm_cmn_debugfs_init(struct arm_cmn *cmn, int id) {} >> >> struct arm_cmn_hw_event { >> struct arm_cmn_node *dn; >> - u64 dtm_idx[4]; >> + u64 dtm_idx[5]; > > Can't we size this based on CMN_MAX_DIMENSION (or CMN_MAX_XPS or > CMN_MAX_DTMS), to make that clear? Fair enough, I did go back and forth a little on that idea, but reached the opposite conclusion that documenting this with the assert to deliberately make it *not* look straightforward was nicer than wrestling with an accurate name for the logical quantity here, which strictly would be something like CMN_MAX_NODES_PER_TYPE_WE_CARE_ABOUT (there can already be up to 256 RN-Fs, but those aren't visible to the PMU). I'll have another think on that approach - I do concur that the assert isn't *functionally* any better than automatically sizing the array. Thanks, Robin. > From the desciription in the commit message it sounds like you need 2 * > CMN_MAX_XPS bits, i.e. > > #define DTM_IDX_BITS (2 * CMN_MAX_XPS) > > u64 dtm_idx[DIV_ROUND_UP(DTM_IDX_BITS, 64)]; > > Mark. > >> s8 dtc_idx[CMN_MAX_DTCS]; >> u8 num_dns; >> u8 dtm_offset; >> -- >> 2.39.2.101.g768bb238c484.dirty >>