scheduler

We are writing a highly concurrent software in C++ for a few hosts, all equipped with a single ST9500620NS as the system drive and an Intel P3700 NVMe Gen3 PCIe SSD card for data. Trying to understand the system more for tuning our software, I dug around the system (two E5-2620 v2 @ 2.10GHz CPUs, 32GB RAM, running CentOS 7.0) and was surprised to spot the following: [root@sc2u0n0 ~]# cat /sys/block/nvme0n1/queue/scheduler none This contradicts to everything that I learned about selecting the correct Linux I/O scheduler, such as from the official doc on kernel.org . I understand that NVMe is a

What's an efficient way to calculate the next run time of an event given the current time and a cron spec? I'm looking for something other than "loop through every minute checking if it matches spec". Examples of specs might be: Every month, on the 1st and 15 at 15:01 At 10,20,30,40,50 mins past the hour every hour Python code would be lovely but psuedo code or high level description would also be appreciated. [Update] Assume the spec is already parsed and is in some reasonable format. Just looking at it, I think you need to: parse the chron spec to five arrays containing acceptable values for

I have a ScheduledThreadPoolExecutor with which I schedule a task to run at a fixed rate. I want the task to be running with a specified delay for a maximum of say 10 times until it "succeeds". After that, I will not want the task to be retried. So basically I'll need to stop running the scheduled task when I want it to be stopped, but without shutting down the ScheduledThreadPoolExecutor. Any idea how I'd do that? Here's some pseudocode - public class ScheduledThreadPoolExecutorTest { public static ScheduledThreadPoolExecutor executor = new ScheduledThreadPoolExecutor(15); // no multiple

I am new to the world of Hadoop and want to know the difference between fair and capacity schedulers. Also when are we supposed to use each one? Please answer in a simple way because I read many things on the Internet but I don't get much from them. Fair scheduling is a method of assigning resources to jobs such that all jobs get, on average, an equal share of resources over time. When there is a single job running, that job uses the entire cluster. When other jobs are submitted, tasks slots that free up are assigned to the new jobs, so that each job gets roughly the same amount of CPU time.

In linux, the scheduler will be triggered when a specific amount of time has passed. As I understood, the timer triggers an interrupt which in turn triggers a call to schedule . In a SMP system, I read in the book "Understanding the Linux Kernel" that "each processor runs the scheduler() function on its own". Does this mean every timer interrupt triggers every cpus to do a re-schedule at the same time? artless noise The ARM SMP systems support two types of interrupts. SPI (shared peripheral interrupt) and PPI (peripheral private interrupts). The PPI is a per-CPU interrupt source. A special

Linux perf tools (some time ago named perf_events ) has several builtin universal software events. Two most basic of them are: task-clock and cpu_clock (internally called PERF_COUNT_SW_CPU_CLOCK and PERF_COUNT_SW_TASK_CLOCK ). But what is wrong with them is lack of description. ysdx user reports that man perf_event_open has short description: PERF_COUNT_SW_CPU_CLOCK This reports the CPU clock, a high-resolution per- CPU timer. PERF_COUNT_SW_TASK_CLOCK This reports a clock count specific to the task that is running. But the description is hard to understand. Can somebody give authoritative

Is it possible to crate a job that will trigger immediately ? when i want the job to be triggres now i builed a cron expression string with the current date and time - i think it's too complicated, is there another way to trigger the job immediately ? Thank's In Advance. All the Jobs registered in the Quartz Scheduler are uniquely identified by the JobKey which is composed of a name and group . You can fire the job which has a given JobKey immediately by calling triggerJob(JobKey jobKey) of your Scheduler instance. //Create a new Job JobKey jobKey = JobKey.jobKey("myNewJob", "myJobGroup");

I need to transfer some data from SQL Server to MySQL, once a month. I have already done this transfer stuff, but I don't know (and I have not found out on the internet) how to set a timer that executes this transfer a specific day every month. I don't want just to set a timer interval in milliseconds because the number of days vary from one month to another. Any help is appreciated... You could use the Windows Task Scheduler for this kind of work. Look here for command line options of Schtasks (there's tons of them) Example 1: To schedule a task that runs on the first day of every month The

im the new in Quartz.NET (v.3.0.3).I have console application and it's quartz host and broadcasting tcp.x:555/QuartzScheduler . In my company we have 2 app server machines and they're master-slave themselves.If master app is down slave take it's place.We will setup console application ( as a service ) in these servers. If we do that what happens in Quartz.NET , is these schedulers will be same or different ? PS: we're using MsSQL jobStore (AdoNetJobStore). Thank you for reply. I found my own solution in this page ; Quartz.NET Clustering I duplicate my console app and change port address (1 :