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 0D96DC001E0 for ; Mon, 23 Oct 2023 10:27:34 +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:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=HXqpokiP7m9h/poy4gVOneG5yMLqbe0EhP/ixSak+Yg=; b=VEqUHo9gpKkxaN ruhnSsk0LOlA0ptMenxbEN4xScZ5qggZUMVwn3w4YdwCcuV8LJM+LCRcuEWZ3YoGIi/vErhbIUeFs PMH7qqRGxEZpFE5PRWgA0ROj6jW1ohdNiBWiJbRa2vwQyENn7BumdVtFClLmzLzdylJWwV38dota4 grbypX/TyLXgxcJYSJymv5G2GCI6i2KLTxvYps4O5Zh1JY6+jTPVa258x8avvQod2L/v7ihtn6elj gBmw8XANzpRssvo4sQQeb7LkezPlgNxjGDL3CmAwCzjZQBnJRRppp+jSiFcH3eoRAen2XETBF3eVY O/Vamel+1zX/VMxf1/5g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qus9H-0071en-2c; Mon, 23 Oct 2023 10:27:03 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qus9E-0071dy-1b for linux-arm-kernel@lists.infradead.org; Mon, 23 Oct 2023 10:27:01 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 7472261D15; Mon, 23 Oct 2023 10:26:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B2EBDC433C7; Mon, 23 Oct 2023 10:26:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1698056819; bh=afivWCmIm1aktOqOx8GKzP/u0SdUkx/ZPjFi3uQ5QoY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=t5sQ6uUhKHt4AYjqto1zWQILEcwCkGiLbptQaRMMzu/7tzIoKD+Z3M/ca4zqpJzSL Zph2LGqA7OQF8LJeTKOMGWG3G0Xc98fupJMalJj4OC2kRjtlklJOj53Qrz7R6RRLWK wEGi9xp2kF0KjMcvlcEtaln+sXTxck1lFZv+Pivu33FTDYKeuvp2wrZwlYXyWDZOuv nzdAcYskrTAiDhgWyJ32HC+UKSrWv4ucncVva67vpwIxFsgXRsjCcKIwipTgF9PnQJ RNnmFeI98M/Vi7b5lc7AGDSaIB0NyoNxZzI28Zt8qvVOsGdkoo1wdlCjb6F0jSHXzv AYsx0GinABaWQ== Date: Mon, 23 Oct 2023 11:26:54 +0100 From: Will Deacon To: Robin Murphy Cc: mark.rutland@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, jeremy.linton@arm.com, ilkka@os.amperecomputing.com, renyu.zj@linux.alibaba.com Subject: Re: [PATCH 2/3] perf/arm-cmn: Rework DTC counters (again) Message-ID: <20231023102653.GA3282@willie-the-truck> References: <5f6ade76b47f033836d7a36c03555da896dfb4a3.1697824215.git.robin.murphy@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <5f6ade76b47f033836d7a36c03555da896dfb4a3.1697824215.git.robin.murphy@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231023_032700_645119_12B0ED8D X-CRM114-Status: GOOD ( 24.37 ) 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 Fri, Oct 20, 2023 at 06:51:26PM +0100, Robin Murphy wrote: > The bitmap-based scheme for tracking DTC counter usage turns out to be a > complete dead-end for its imagined purpose, since by the time we have to > keep track of a per-DTC counter index anyway, we already have enough > information to make the bitmap itself redundant. Revert the remains of > it back to almost the original scheme, but now expanded to track per-DTC > indices, in preparation for making use of them in anger. > > Note that since cycle count events always use a dedicated counter on a > single DTC, we reuse the field to encode their DTC index directly. > > Signed-off-by: Robin Murphy > --- > drivers/perf/arm-cmn.c | 126 +++++++++++++++++++++-------------------- > 1 file changed, 64 insertions(+), 62 deletions(-) > > diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c > index f1ac8d0cdb3b..675f1638013e 100644 > --- a/drivers/perf/arm-cmn.c > +++ b/drivers/perf/arm-cmn.c > @@ -281,16 +281,13 @@ struct arm_cmn_node { > u16 id, logid; > enum cmn_node_type type; > > - int dtm; > - union { > - /* DN/HN-F/CXHA */ > - struct { > - u8 val : 4; > - u8 count : 4; > - } occupid[SEL_MAX]; > - /* XP */ > - u8 dtc; > - }; > + u8 dtm; > + s8 dtc; > + /* DN/HN-F/CXHA */ > + struct { > + u8 val : 4; > + u8 count : 4; > + } occupid[SEL_MAX]; > union { > u8 event[4]; > __le32 event_sel; > @@ -540,12 +537,12 @@ static int arm_cmn_map_show(struct seq_file *s, void *data) > > seq_puts(s, "\n |"); > for (x = 0; x < cmn->mesh_x; x++) { > - u8 dtc = cmn->xps[xp_base + x].dtc; > + s8 dtc = cmn->xps[xp_base + x].dtc; > > - if (dtc & (dtc - 1)) > + if (dtc < 0) > seq_puts(s, " DTC ?? |"); > else > - seq_printf(s, " DTC %ld |", __ffs(dtc)); > + seq_printf(s, " DTC %d |", dtc); > } > seq_puts(s, "\n |"); > for (x = 0; x < cmn->mesh_x; x++) > @@ -589,8 +586,7 @@ 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]; > - unsigned int dtc_idx; > - u8 dtcs_used; > + s8 dtc_idx[CMN_MAX_DTCS]; > u8 num_dns; > u8 dtm_offset; > bool wide_sel; > @@ -600,6 +596,10 @@ struct arm_cmn_hw_event { > #define for_each_hw_dn(hw, dn, i) \ > for (i = 0, dn = hw->dn; i < hw->num_dns; i++, dn++) > > +/* @i is the DTC number, @idx is the counter index on that DTC */ > +#define for_each_hw_dtc_idx(hw, i, idx) \ > + for (int i = 0, idx; i < CMN_MAX_DTCS; i++) if ((idx = hw->dtc_idx[i]) >= 0) This macro is pretty hideous ;) The kbuild robot complained as well, but given that it's internal to the driver and it does make the callsites quite a bit simpler, I'm inclined to stick with it for now. At least, I couldn't come up with something else which was just as succinct. Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel