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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6F7EFC4332F for ; Wed, 14 Dec 2022 16:09:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238760AbiLNQJc (ORCPT ); Wed, 14 Dec 2022 11:09:32 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36958 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238763AbiLNQJZ (ORCPT ); Wed, 14 Dec 2022 11:09:25 -0500 Received: from mail-yw1-x114a.google.com (mail-yw1-x114a.google.com [IPv6:2607:f8b0:4864:20::114a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8EECC23BE2 for ; Wed, 14 Dec 2022 08:09:24 -0800 (PST) Received: by mail-yw1-x114a.google.com with SMTP id 00721157ae682-3ceb4c331faso2692977b3.2 for ; Wed, 14 Dec 2022 08:09:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=VGK0E4ycnuqQrwZSaCfYQzl+oEBemoUae4RgweF6XeQ=; b=XGAKWHiuWQFlu6EENpET/7efF/JlU9+FcquL8yQ4TGnbRqLL65ipCmxc3rOvoxOka/ S6QrwJSh7Fjj7peGO0pPnSrfiQcwQNwQezXo7H4yUSsDHjPCa7RVKgkBnOUP3nIgKxBZ prMzsbdmMXNx3oSpVLq9WUva71y+kaEx05Q+Otqupx5ZRJ2RQ/dZMOgOavcsclDMB7Ci YogqNiUBwBxKg0rSZ4a8HdyIPxjxeLR+dmKOJEdwf+HRjTa7rGe6eJ40zxW2Z0H+FM6d NZUhgw6UjnMaPsYXWkVVFzwtsA7ybPBT8VWNjEG7B5YUvZKrogSQ8fIHARqbYW8hQJ6y DjJA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=VGK0E4ycnuqQrwZSaCfYQzl+oEBemoUae4RgweF6XeQ=; b=Lwr68T9fnubWZlncj2KbxmCuijZ0QTdAjmpxNxmVPWbHahRVlTK1oRnkErhgj9VpQS Roc+Ez3Z5qwmn/u4zW2Ku3ILhqYpYBcuT7gjGXkBf2ir51PUtG8Bs3M1aORLQNfB9r4K 09zXX1uRNenW3XtSVXVYV8hYVWVvoiEmgbpkT8w75lmzEoRpPifoqMv4JYD0qWlBSHYP v3BncV9Op6eVNUIJ9jNhEjzAXDFVwELaXtg2s5AZjx6j5vC5D++dpeFVHWf6XOQ3n6Qh YtM9EkyDPmXIyWw65wqGGx0uNsF+hhoiy3jj1f5ne8F0r7yRA2U7+VM45J65HceEV8FO VpJQ== X-Gm-Message-State: ANoB5pnumZYc5DEZuINvj+ShU2bpJUtXejijhN/3AfMT6BC4smbYZEDc ZNpmvyDqAtftafHt+JcwPEUR0BT99+iN3/eu1g== X-Google-Smtp-Source: AA0mqf77KJ67F5HAQFySn17fQ9wG6CMCnQ/0Z9VqeKejeVmk8QOh9V8HQdsIgvGCA//776i30gaIHbyapnpSifhwTw== X-Received: from peternewman-vh.c.googlers.com ([fda3:e722:ac3:cc00:28:9cb1:c0a8:30cc]) (user=peternewman job=sendgmr) by 2002:a25:9006:0:b0:705:2982:c937 with SMTP id s6-20020a259006000000b007052982c937mr10617289ybl.420.1671034163807; Wed, 14 Dec 2022 08:09:23 -0800 (PST) Date: Wed, 14 Dec 2022 17:08:56 +0100 In-Reply-To: <20221214160856.2164207-1-peternewman@google.com> Mime-Version: 1.0 References: <20221214160856.2164207-1-peternewman@google.com> X-Mailer: git-send-email 2.39.0.rc1.256.g54fd8350bd-goog Message-ID: <20221214160856.2164207-2-peternewman@google.com> Subject: [PATCH v2 2/2] x86/resctrl: Avoid redundant counter read in __mon_event_count() From: Peter Newman To: reinette.chatre@intel.com, fenghua.yu@intel.com Cc: Babu.Moger@amd.com, bp@alien8.de, dave.hansen@linux.intel.com, eranian@google.com, hpa@zytor.com, james.morse@arm.com, linux-kernel@vger.kernel.org, mingo@redhat.com, quic_jiles@quicinc.com, tan.shaopeng@fujitsu.com, tglx@linutronix.de, x86@kernel.org, Peter Newman Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org __mon_event_count() does the per-RMID, per-domain work for user-initiated event count reads and the initialization of new monitor groups. In the initialization case, after resctrl_arch_reset_rmid() calls __rmid_read() to record an initial count for a new monitor group, it immediately calls resctrl_arch_rmid_read(). This re-read of the hardware counter is unnecessary. Following return from resctrl_arch_reset_rmid(), just clear the mbm_state and return. Also, move the mbm_state lookup into the rr->first case, as it's not needed for regular event count reads: the QOS_L3_OCCUP_EVENT_ID case was redundant with the accumulating logic at the end of the function. Signed-off-by: Peter Newman --- arch/x86/kernel/cpu/resctrl/monitor.c | 43 ++++++++++++--------------- 1 file changed, 19 insertions(+), 24 deletions(-) diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c index 77538abeb72a..e708df478077 100644 --- a/arch/x86/kernel/cpu/resctrl/monitor.c +++ b/arch/x86/kernel/cpu/resctrl/monitor.c @@ -366,41 +366,36 @@ void free_rmid(u32 rmid) list_add_tail(&entry->list, &rmid_free_lru); } +static struct mbm_state *get_mbm_state(struct rdt_domain *d, u32 rmid, + enum resctrl_event_id evtid) +{ + switch (evtid) { + case QOS_L3_MBM_TOTAL_EVENT_ID: + return &d->mbm_total[rmid]; + case QOS_L3_MBM_LOCAL_EVENT_ID: + return &d->mbm_local[rmid]; + default: + return NULL; + } +} + static int __mon_event_count(u32 rmid, struct rmid_read *rr) { struct mbm_state *m; u64 tval = 0; - if (rr->first) + if (rr->first) { resctrl_arch_reset_rmid(rr->r, rr->d, rmid, rr->evtid); + m = get_mbm_state(rr->d, rmid, rr->evtid); + if (m) + memset(m, 0, sizeof(struct mbm_state)); + return 0; + } rr->err = resctrl_arch_rmid_read(rr->r, rr->d, rmid, rr->evtid, &tval); if (rr->err) return rr->err; - switch (rr->evtid) { - case QOS_L3_OCCUP_EVENT_ID: - rr->val += tval; - return 0; - case QOS_L3_MBM_TOTAL_EVENT_ID: - m = &rr->d->mbm_total[rmid]; - break; - case QOS_L3_MBM_LOCAL_EVENT_ID: - m = &rr->d->mbm_local[rmid]; - break; - default: - /* - * Code would never reach here because an invalid - * event id would fail in resctrl_arch_rmid_read(). - */ - return -EINVAL; - } - - if (rr->first) { - memset(m, 0, sizeof(struct mbm_state)); - return 0; - } - rr->val += tval; return 0; -- 2.39.0.rc1.256.g54fd8350bd-goog