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Eric reported a sysbench regression against commit:3fed382b46("sched/numa: Implement NUMA node level wake_affine()") Similarly, Rik was looking at the NAS-lu.C benchmark, which regressed against his v3.10 enterprise kernel. PRE (current tip/master): ivb-ep sysbench: 2: [30 secs] transactions: 64110 (2136.94 per sec.) 5: [30 secs] transactions: 143644 (4787.99 per sec.) 10: [30 secs] transactions: 274298 (9142.93 per sec.) 20: [30 secs] transactions: 418683 (13955.45 per sec.) 40: [30 secs] transactions: 320731 (10690.15 per sec.) 80: [30 secs] transactions: 355096 (11834.28 per sec.) hsw-ex NAS: OMP_PROC_BIND/lu.C.x_threads_144_run_1.log: Time in seconds = 18.01 OMP_PROC_BIND/lu.C.x_threads_144_run_2.log: Time in seconds = 17.89 OMP_PROC_BIND/lu.C.x_threads_144_run_3.log: Time in seconds = 17.93 lu.C.x_threads_144_run_1.log: Time in seconds = 434.68 lu.C.x_threads_144_run_2.log: Time in seconds = 405.36 lu.C.x_threads_144_run_3.log: Time in seconds = 433.83 POST (+patch): ivb-ep sysbench: 2: [30 secs] transactions: 64494 (2149.75 per sec.) 5: [30 secs] transactions: 145114 (4836.99 per sec.) 10: [30 secs] transactions: 278311 (9276.69 per sec.) 20: [30 secs] transactions: 437169 (14571.60 per sec.) 40: [30 secs] transactions: 669837 (22326.73 per sec.) 80: [30 secs] transactions: 631739 (21055.88 per sec.) hsw-ex NAS: lu.C.x_threads_144_run_1.log: Time in seconds = 23.36 lu.C.x_threads_144_run_2.log: Time in seconds = 22.96 lu.C.x_threads_144_run_3.log: Time in seconds = 22.52 This patch takes out all the shiny wake_affine() stuff and goes back to utter basics. Between the two CPUs involved with the wakeup (the CPU doing the wakeup and the CPU we ran on previously) pick the CPU we can run on _now_. This restores much of the regressions against the older kernels, but leaves some ground in the overloaded case. The default-enabled WA_WEIGHT (which will be introduced in the next patch) is an attempt to address the overloaded situation. Reported-by: Eric Farman <farman@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matthew Rosato <mjrosato@linux.vnet.ibm.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: jinpuwang@gmail.com Cc: vcaputo@pengaru.com Fixes:3fed382b46("sched/numa: Implement NUMA node level wake_affine()") Signed-off-by: Ingo Molnar <mingo@kernel.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.