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Tue, 12 May 2026 14:43:48 -0700 (PDT) Message-ID: <64f465ca-6117-4375-9c4b-af771b8205fd@gmail.com> Date: Tue, 12 May 2026 14:43:46 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Betterbird (Linux) Subject: Re: the stuttering regression in 7.0: should I have done something different Content-Language: en-US To: Thomas Gleixner Cc: Linux kernel regressions list , LKML , sparclinux@vger.kernel.org, John Paul Adrian Glaubitz , Thorsten Leemhuis References: <1c165caf-36b4-4673-97fd-ed86bef17b88@leemhuis.info> <3332123b-9e11-4895-9ab3-1707fba5815c@gmail.com> <871pfj9cmj.ffs@tglx> <088e6cfa-0167-4748-af6c-458ade2f303a@gmail.com> <878q9p82je.ffs@tglx> From: Tony Rodriguez In-Reply-To: <878q9p82je.ffs@tglx> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 5/12/26 1:17 AM, Thomas Gleixner wrote: >> [  249.004209] [<0000000000000000>] 0x0 >> [  249.019116] Dumping ftrace buffer: >> [  249.025666] --------------------------------- >> [  249.034534]   -0         0d.... 1836659us : >> clockevents_program_event: Successfully programmed 4000000 4000000 >> [  249.055418]   -0         0d.h.. 1845926us : timer_interrupt: > So this is the interesting part, but that's starting at 1.836659s > while the actual problem happens ~120 seconds later and the detection > takes another 120 seconds. > > Assuming that one of the CPUs does not get timer interrupts anymore, the > trace of that CPU should end around the time the last programming > happened. So the interesting part is at the end of the output. The > default buffer size per CPU is 1408k, which holds about 150k entries, so > we can just shorten the buffers to make this less painful. > > Can you add 'trace_buf_size=50k' to the kernel command line, which > limits the buffer size to about 640 entries. Assuming 115200 Baud this > should then take about 4 seconds per CPU to dump, which still is a bunch > on a large machine, but definitely way more workable than the default. Done.  The complete trace file "s7-2-05122026-dump.tar.gz" can be obtained from my GitHub repo: https://github.com/unixpro1970/Sparc64-Kernel-Debugging-Dumps > IIRC, SPARC64 S7‑2 has 128 threads total, so the resulting uncompressed > output should be around 7-8M. That's highly compressable text, so the > resulting dump.xz should be suitable to be stored in github. If github > does not allow you, let me know and we work something out. > > Thanks, > > tglx >