"tickless" kernel can improve perf/energy usage. Unwanted jitter for Realtime/HPC workload with a single runnable task Inefficient for light workload with long idle periods.Ģ. To/from idle and transitioning between user/kernel execution.ġ. Purpose: for workloads with many tasks using short bursts of CPU =>įrequent but brief idle periods, reduces the overhead of switching OS (Linux) sets a timer interrupt to wake up the CPU every N ms, called Tag="programming kernel linux compsci c os operating-system" Wait ("grace period") for previous readers to complete their RCU read-side critical section. Remove pointer to data structure, so subsequent readers can’t acquire a reference to it. This copy is hidden from view so that no new references are attached > RCU works by replacing a data structure with a modified version and keeps an > is in the process of being updated: RCU updaters cannot block readers or force
> key property of RCU is that readers can access a data structure even when it > involved, hence they will be fast, but also making updates more difficult. This makes all readers proceed as if there were no synchronization > simultaneously marking the data, ensuring new readers will read the updated > deferring updates after pre-existing reads to a later time while > RCU allows multiple threads to efficiently read from shared memory by > mutex strategy optimized for read-heavy tasks, at the cost of more space. Tag="rcu data-structure adt programming kernel linux compsci os operating-system" $ sudo sysctl -w vm.dirty_background_ratio=10 WORKAROUND: reduce time between fscache->disk flushes. Kernel: Workqueue: writeback wb_workfn (flush-8:0)
Kernel: INFO: task kworker/u24:1:11350 blocked for more than 120 seconds. Kernel: INFO: task pool:14317 blocked for more than 120 seconds. Kernel: call_rwsem_down_write_failed+0x17/0x30 Kernel: INFO: task rsync:5626 blocked for more than 120 seconds. Kernel: INFO: task updatedb.mlocat:8211 blocked for more than 120 seconds. Choose good buffer sizes when performing IO operations. Filesystem disk usage above 80%, excessive fragmentation.
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Not enough free memory for the OS to cache disk blocks. IOWait, if not associated with IO errors (failed resources), may be caused by: Tag="kernel linux io os syscall error troubleshooting filesystem virtual-memory" IOWait, hung IO tasks, "task foo:3450 blocked for more than 120 seconds", hung_task_timeout_secs Tag="todo performance distributed-systems scaling mysql databases" Tag="todo performance unix linux devops sysadmin" Tag="performance checklist linux devops sysadmin" Netflix Tech Blog: Linux Performance Analysis in 60,000 Milliseconds each to cache (referential transparency) defer: queue operations to the last step or an external system concentrate: keep it in a central placeģ. derive (compute) values instead of extra stateĢ. To avoid mutable state and other side-effects:ġ. has functions (closures) as opposed to _procedures_ Tag="clojure functional-programming compsci" Solving Problems the Clojure Way - Rafal Dittwald It is available across several platforms, including Android, iOS, Microsoft Windows, Macintosh operating systems, Linux and macOS.Vim: sw=2 ft=text comments=s1\:/*,mb\:*,ex\:*/,\://,b\:#,\:%,\:XCOMM,n\:>,fb\:. Motorsport Manager is a single-player game that was released in 2014. From minute details, like the components of your car and race-day decisions, to big-picture tasks like assembling your team and voting on rules and regulations for the sport, there is a wealth of content at every level. The early portion of the game is heavy on tutorials to ease you into things, so you aren't just left spinning your wheels. You will quickly find, as is so often the case with business simulators, that there is a whole lot more going on behind the scenes than you could have imagined.
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In this simulation game, you manage the team that is responsible for putting a driver on the podium. Motorsport Manager takes you from behind the wheel and puts you behind the team. It is available for purchase on Steam and can be played on Microsoft Windows, Linux, macOS and Macintosh operating systems. You can build factories, transport lines, keep an eye out for the next big thing, find gaps in the market and strike business deals. During the game, you build and manage a growing empire. Have you ever wondered what it'd be like to live in the early 20th century? When you play Rise of Industry, you become an early 20th century industrialist.
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