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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-49c5d03b104sm16969858f8f.6.2026.11.15.04.55.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 15 Nov 2026 04:55:18 -0800 (PST) Date: Sun, 15 Nov 2026 12:55:16 +0000 From: David Laight To: bot+bpf-ci@kernel.org Cc: pmladek@suse.com, kees@kernel.org, linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org, bpf@vger.kernel.org, jim.cromie@gmail.com, ljs@kernel.org, mcgrof@kernel.org, andrey.grodzovsky@crowdstrike.com, rostedt@goodmis.org, andrii@kernel.org, wusamuel@google.com, linux-kselftest@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net, martin.lau@kernel.org, eddyz87@gmail.com, yonghong.song@linux.dev, mason@kernel.org, ihor.solodrai@linux.dev Subject: Re: [PATCH v3 next 06/13] kallsyms: Improve selftest test_perf_kallsyms_lookup_name() output Message-ID: <20261115125517.362eeb4a@pumpkin> In-Reply-To: <54d7eddad4b50bbaa72bc31ea3219ce9a944548da1fef3eabbc1e7337d37e5f2@mail.kernel.org> References: <20261111115911.1142000-7-david.laight.linux@gmail.com> <54d7eddad4b50bbaa72bc31ea3219ce9a944548da1fef3eabbc1e7337d37e5f2@mail.kernel.org> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Wed, 11 Nov 2026 23:17:06 +0000 (UTC) bot+bpf-ci@kernel.org wrote: > > kallsyms: Improve selftest test_perf_kallsyms_lookup_name() output > > TL;DR: Commit message only: it says 4 functions get noinline_for_stack but the > patch marks 5, and it omits the compression-ratio output format fix; maybe > split that into a separate patch. > > > kallsyms: Improve selftest test_perf_kallsyms_lookup_name() output > > > > - Improve the test stability/reproducability by taking the faster of > > two calls to kallsyms_lookup_name(). > > - Check that kallsyms_lookup_name() returns the expected address > > unless the symbol is duplicated. > > - Report the names of the min/max symbols. > > - Output an 8 line 64 entry histogram of the times taken. > > - This shows there is a reasonably normal distribution with a small > > number of much slower outliers that don't really affect the average. > > > > Additionally: > > - Add a very long symbol to check the handling of two byte lengths. > > - Do the test_perf_kallsyms_lookup_name() last because it can take long > > enough that the CPU frequency changes and the times reported by the > > other tests can change. > > - Mark the 4 test functions noinline_for_stack since they all have a > > quite large on-stack structure. > > > > Example output (after all these patches) > > kallsyms_on_each_symbol() traverse all: 7742950 ns > > kallsyms_on_each_match_symbol() traverse all: 951 ns > > kallsyms_lookup_name() looked up 123312 symbols, average 200 ns > > fastest 60 ns (_rs.0) > > slowest 662 ns (The_time_has_come_the_Walrus_said_To_talk_of_many_things_Of_sho) > > Distribution, 20ns per column, 2916 counts per *: > > | ** > > | **** > > | **** > > | **** > > | ****** > > | ******* > > | ********* > > | ****************** ** * * * > > > > Signed-off-by: David Laight > > > > The changelog says 4 test functions are marked noinline_for_stack "since they > all have a quite large on-stack structure", but the patch marks five: > test_kallsyms_compression_ratio(), test_perf_kallsyms_lookup_name(), > test_perf_kallsyms_on_each_symbol(), test_perf_kallsyms_on_each_match_symbol() > and test_kallsyms_basic_function(). > > test_kallsyms_compression_ratio() has only seven u32 locals and no large > on-stack structure, so the stated reason does not cover it. The large stack frame is hidden, it is inside kallsyms_on_each_symbol(). So the commit message should probably just say 'all'. > > The same function also changes its output format from "%2d.%-2d" to > "%2d.%02d", which fixes how the fractional part is printed (12.05 used to show > as "12.5 "). The changelog does not mention this. I mentioned in it the changes for v3 lower down. David > Could the changelog give the right count and mention the format fix, or should > the compression-ratio changes go in a separate patch? > > > --- > AI reviewed your patch. Please fix the bug or email reply why it's not a bug. > See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md > > CI run summary: https://github.com/kernel-patches/bpf/actions/runs/43116767394