From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 87E7346AA76; Tue, 4 Aug 2026 17:16:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785863774; cv=none; b=QVilxGvngPJleryUwbtkVrC30malBO5Mh/KqhGQQAEWHHbePri7we0avbKvBvvjDktZ4ghb1berI2CDWnim8AuUaPAORNVyHWghVqBS3PGKV6uOEES23mjzm14C4JhmP8+BAgdkCSFSMct6RvTl8WvDrhEriMHBKjsft+3aMHdU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785863774; c=relaxed/simple; bh=+UhG3zAbCzryuhJl5ulcHn4rRXU7jh8zBKSUT7+NM0I=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ux1Sqixl9GsuCunvDqqXiSJlcHQjHGmyGmq0zplhV9mc/8i9VJHGIQ3vyGHDDWqcAEJW9HZOfMZiafj3CRka+eWkUUTgS+wC56GuFapBCoWMCvVzlB1II67BF4Rm9jegv4coBZo2wjpVBDjWMlGCHosQJLv8BcBYCLpvCXInD2E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=gVsEqxER; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="gVsEqxER" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0582B1F000E9; Tue, 4 Aug 2026 17:16:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785863762; bh=7sNZpEQ0zMR1Ta0y6y9ln6xHRlY7xpsNchHx3GFDdME=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=gVsEqxERy5tKiimCIoGtPqXMpE+prx4NpFwbJVR8CX8wSUQn/rJYZMeaC1uVyJ2Xs aDCbTSPk4RDUIuENyUIS6hsIagIEzNVWU7FcyNpRDsJ22B7qEYTNJgeXZVA/Fgqyl4 7TpniFDr1nPl3lJo5lqT8/GmTVAOUpmX7DUBYAZruGUvisliBBp34lUr37u9469Wl9 z8nScm4SMJAx3QcaanSm9zkLOIcJ0tNTBNhoD9ZD4uYJV7TH6E0H0bAS2W27pIhnhw +Stqa+PeNevSRLakRAY3wGgk/dzQdthjAVetT5mD5nzjQNtF1JOztebu3F2Dcr9No/ cqf2WSnD/yJdg== Date: Tue, 4 Aug 2026 10:15:59 -0700 From: Namhyung Kim To: Jiebin Sun Cc: acme@kernel.org, mingo@redhat.com, peterz@infradead.org, adrian.hunter@intel.com, alexander.shishkin@linux.intel.com, irogers@google.com, james.clark@linaro.org, jolsa@kernel.org, mark.rutland@arm.com, dapeng1.mi@linux.intel.com, thomas.falcon@intel.com, tianyou.li@intel.com, wangyang.guo@intel.com, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v6 0/9] perf c2c: add a function view Message-ID: References: <20260803035220.172022-1-jiebin.sun@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260803035220.172022-1-jiebin.sun@intel.com> Hello, On Mon, Aug 03, 2026 at 11:52:11AM +0800, Jiebin Sun wrote: > This series adds a new "function view" to perf c2c report, on top of the > existing cacheline view. Existing cacheline-view data and operations remain > unchanged; TAB adds access to a complementary way to inspect the same > cache-to-cache (C2C) data. > > v1: https://lore.kernel.org/linux-perf-users/20260626070355.1556721-1-jiebin.sun@intel.com/ > v2: https://lore.kernel.org/linux-perf-users/20260710084247.3576706-1-jiebin.sun@intel.com/ > v3: https://lore.kernel.org/linux-perf-users/20260717020530.1645123-1-jiebin.sun@intel.com/ > v4: https://lore.kernel.org/linux-perf-users/20260724095842.995920-1-jiebin.sun@intel.com/ > v5: https://lore.kernel.org/linux-perf-users/20260730090521.2206375-1-jiebin.sun@intel.com/ > > Changes since v5 > ================ > > - Give the function-view children their own references instead of > borrowing them, as suggested by Namhyung. They set ops and take refs > via map_symbol__copy() and thread__get(), so hist_entry__delete() > frees them; the custom child destructor and the > WARN_ON_ONCE(report_hierarchy) guard are gone. > > - Add NO_SLANG stubs for the two TUI entry points declared in c2c.h, > matching how util/hist.h declares its own. > > - Spell out in the symbol renderer why the length returned by > se_snprintf() cannot exceed the cell. > > - Rebase onto perf-tools-next at d04ef71492fa. > > No intended change to the rendered output, cacheline-view data, existing > cacheline operations, or --stdio output. I'm about to merge the series. But please consider a follow-up work to add support for --stdio and add a test case. Thanks, Namhyung > > Changes since v4 > ================ > > - Rebase onto perf-tools-next at 0d40fedcd1b9. > > - Require `iaddr` in --coalesce before entering the function view; > without it, coalesced samples cannot be reliably attributed. > > - Reuse each source cacheline's existing index as the level-3 identity, > so same-address sources no longer merge and 'd' finds the original > entry, without adding fields to the shared C2C structures. > > - Keep same-function reader/writer pairs, which the coalesced view cannot > reliably tell apart from cross-thread contention. > > - Robustness and cleanup: build the hierarchy only from filtered > cachelines with a lightweight entry allocator; explicit > mem_info__new() handling; a local bound in the symbol renderer; a > NULL-map guard; deterministic tie-breaks; function-view-local row > recounting; Ctrl-C as an exit key; and expanded man-page docs. > > Changes since v3 > ================ > > Reworked the function view into a true function-centric hierarchy, as > discussed with Namhyung: > > - Level 1 is the read-side function itself, aggregating all of its code > addresses into one entry and sorting by Cycles %. > > - Level 2 is the contending function that writes the shared lines, > aggregated across cachelines and sorted by store count. Level 3 is the > specific cachelines. > > - Dedicated code-address and offset columns were removed from the main > view. Verbose function formatting can still include a representative > code address, and full code-address information remains available in > the per-cacheline detail view ('d'). > > - Lower-level entries are indented like the normal perf report hierarchy > view, and entries with no contending writer are pruned. > > - Reorganized the series from 14 mechanical patches into 9 logically > self-contained patches. > > Changes since v2 > ================ > > - Prefix helpers exported from builtin-c2c.c with c2c_, as suggested by > Namhyung. > > Changes since v1 > ================ > > - Add a worked man-page example, as suggested by Namhyung. > > In the perf c2c TUI, press TAB in the cacheline view to switch to the > function view. It presents a three-level hierarchy: > > Level 1: read-side function, sorted by Cycles % > Level 2: functions writing the shared lines, sorted by store count > Level 3: cachelines where the two functions contend > > For example, with dequeue_pushable_task expanded to its level-2 writers and > two of those writers expanded to their level-3 cachelines: > > Shared Data Functions Table (19 entries, sorted on Cycles %) > Cycles Store > % count Function / Contending function / Cacheline > ---------------------------------------------------------------------- > + 35.67% 876 + [k] cpupri_set > + 24.31% 424 + [k] pull_rt_task > - 16.53% 555 - [k] dequeue_pushable_task > 145 - [k] pull_rt_task > 145 0xff2d0082809da080 > 139 - [k] enqueue_pushable_task > 70 0xff2d00a2071f9640 > 69 0xff2d0082809da000 > > A level-1 store count decomposes into its level-2 writers, and each writer's > count decomposes into its level-3 cachelines (here 145 = 145, 139 = 70 + 69). > > Keys in the function view: > > TAB/ESC/q/Ctrl-C return to the cacheline view > d show details for the selected level-3 cacheline > e / + expand / collapse the selected entry > ? help > > The function view is a separate hist_browser in > tools/perf/ui/browsers/c2c-function.c. Shared types and helpers used by > both views are factored out of builtin-c2c.c into c2c.h. The hierarchy is > constructed from the existing cacheline histograms into dedicated hists > and rendered with custom column formatters. > > Testing: each commit builds individually; the full series builds with and > without SLANG support; perf test c2c passes (one permission-related skip); > cacheline --stdio output is byte-identical to the base commit; and the > perf-c2c man page builds. > > Jiebin Sun (9): > perf c2c: extract shared data structures into c2c.h > perf c2c: add function view browser skeleton > perf c2c: add column rendering for function view > perf c2c: add HPP list parsing for function view columns > perf c2c: add function view stats merge and memory management > perf c2c: add function view hierarchy entry creation > perf c2c: build and finalize the function view hierarchy > perf c2c: add function view browser UI and cacheline detail > perf c2c: document function view in perf-c2c man page > > tools/perf/Documentation/perf-c2c.txt | 71 + > tools/perf/builtin-c2c.c | 130 +- > tools/perf/c2c.h | 155 +++ > tools/perf/ui/browsers/Build | 1 + > tools/perf/ui/browsers/c2c-function.c | 1783 +++++++++++++++++++++++++ > 5 files changed, 2021 insertions(+), 119 deletions(-) > create mode 100644 tools/perf/c2c.h > create mode 100644 tools/perf/ui/browsers/c2c-function.c > > > base-commit: d04ef71492fad7230d474efe33d05f4c0563d409 > -- > 2.52.0 >