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HAS_REPLYTO(0.30)[pvorel@suse.cz]; NEURAL_HAM_SHORT(-0.20)[-0.999]; MIME_GOOD(-0.10)[text/plain]; ARC_NA(0.00)[]; FUZZY_RATELIMITED(0.00)[rspamd.com]; MIME_TRACE(0.00)[0:+]; RCVD_VIA_SMTP_AUTH(0.00)[]; TO_DN_SOME(0.00)[]; MISSING_XM_UA(0.00)[]; RCVD_TLS_ALL(0.00)[]; RCPT_COUNT_FIVE(0.00)[5]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.cz:replyto]; REPLYTO_EQ_FROM(0.00)[] X-Virus-Scanned: clamav-milter 1.0.7 at in-6.smtp.seeweb.it X-Virus-Status: Clean Subject: Re: [LTP] [PATCH v2] sched_football: synchronize with kickoff flag to reduce skew X-BeenThere: ltp@lists.linux.it X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux Test Project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Petr Vorel Cc: ltp@lists.linux.it Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ltp-bounces+ltp=archiver.kernel.org@lists.linux.it Sender: "ltp" Hi all, ... > Checking the configurations of the stock kernel and the real-time > kernel, the stock kernel uses "CONFIG_PREEMPT_VOLUNTARY=y," > which only provides voluntary preemption. Yes, CONFIG_PREEMPT_VOLUNTARY=y is in all mainline defconfigs (arch/*/configs/*_defconfig). Therefore we have it in our Tumbleweed (6.16.3-1) and in upcoming SLES16 (6.12 based). SLE15-SP7 (6.4 based) use CONFIG_PREEMPT_NONE=y instead. Looking at the history It works well on all archs, we just recently had a problem with ppc64le hmc on SLE16 (regular ppc64le works). Later I'll check history of older SLES versions. And most importantly I'll try to run manually with -i (more stress test). > This preemption model is designed to strike a balance between throughput > and latency. It only allows the kernel to be preempted at specific, well > defined > "safe points," potentially resulting in long, unbounded latencies. > However, the sched_football test was most likely designed to measure or > stress-test the deterministic, low-latency scheduling behavior that is > characteristic of real-time (RT) kernel. > So, I tend to believe the test's failure on the stock kernel is acceptable. > And, by the way, what does the SUSE kernel configuration look like? > # grep CONFIG_PREEMPT /boot/config-6.12.0-55.29.1.el10_0.x86_64 > CONFIG_PREEMPT_BUILD=y > CONFIG_PREEMPT_VOLUNTARY=y > # CONFIG_PREEMPT is not set > # CONFIG_PREEMPT_RT is not set > CONFIG_PREEMPT_COUNT=y > CONFIG_PREEMPTION=y > CONFIG_PREEMPT_DYNAMIC=y > CONFIG_PREEMPT_RCU=y > CONFIG_PREEMPT_NOTIFIERS=y > (^ I built my v6.17-rc4 with this config too) /boot/config-6.12.0-160000.4-default # Tumbleweed x68_64 CONFIG_PREEMPT_BUILD=y # CONFIG_PREEMPT_NONE is not set CONFIG_PREEMPT_VOLUNTARY=y # CONFIG_PREEMPT is not set # CONFIG_PREEMPT_LAZY is not set # CONFIG_PREEMPT_RT is not set CONFIG_PREEMPT_COUNT=y CONFIG_PREEMPTION=y CONFIG_PREEMPT_DYNAMIC=y CONFIG_PREEMPT_RCU=y CONFIG_PREEMPT_NOTIFIERS=y # CONFIG_PREEMPT_TRACER is not set CONFIG_PREEMPTIRQ_DELAY_TEST=m Upcoming SLE16 is similar to Tumbleweed. /boot/config-6.4.0-150700.714.ga8e7017-default # SLE15-SP7 x86_64 RT CONFIG_PREEMPT_BUILD=y CONFIG_PREEMPT_NONE=y # CONFIG_PREEMPT_VOLUNTARY is not set # CONFIG_PREEMPT is not set # CONFIG_PREEMPT_RT is not set CONFIG_PREEMPT_COUNT=y CONFIG_PREEMPTION=y CONFIG_PREEMPT_DYNAMIC=y CONFIG_PREEMPT_RCU=y CONFIG_PREEMPT_NOTIFIERS=y # CONFIG_PREEMPT_TRACER is not set CONFIG_PREEMPTIRQ_DELAY_TEST=m /boot/config-6.4.0-150700.5-rt # SLE15-SP7 x86_64 RT CONFIG_PREEMPT_LAZY=y # CONFIG_PREEMPT_NONE is not set # CONFIG_PREEMPT_VOLUNTARY is not set # CONFIG_PREEMPT is not set CONFIG_PREEMPT_RT=y CONFIG_PREEMPT_COUNT=y CONFIG_PREEMPTION=y CONFIG_PREEMPT_RCU=y CONFIG_PREEMPT_NOTIFIERS=y # CONFIG_PREEMPT_TRACER is not set CONFIG_PREEMPTIRQ_DELAY_TEST=m Kind regards, Petr > # grep CONFIG_PREEMPT /boot/config-6.12.0-55.31.1.el10_0.x86_64+rt > CONFIG_PREEMPT_BUILD=y > CONFIG_PREEMPT=y > CONFIG_PREEMPT_RT=y > CONFIG_PREEMPT_COUNT=y > CONFIG_PREEMPTION=y > # CONFIG_PREEMPT_DYNAMIC is not set > CONFIG_PREEMPT_RCU=y > CONFIG_PREEMPT_NOTIFIERS=y -- Mailing list info: https://lists.linux.it/listinfo/ltp