Iowait which process

The simplest way to find the culprit is to use command Iotop, by looking at iotop statistics, we can easily guide sshd as the culprit. Although Iotop is a very powerful tool and is easy to use, it is not installed by default on all Linux operating systems.

And I personally prefer not to rely too much on those commands that are not installed by default. A system administrator may find that he cannot immediately install additional software other than the default program, unless waiting for the next maintenance time. The lsof command can show all the files that a process opens, or all the processes that open a file. In order to further confirm that these files are read and written frequently, we can view them with the following command.

With the above information we can safely say that the result of lsof is the file we are looking for. ApsaraDB for Redis Redis.

Thanks in advance, Regards, Bache 3 Replies. RedHat Commands. OpenSolaris Commands. Linux Commands. SunOS Commands. FreeBSD Commands. Full Man Repository. Advanced Search. Contact Us. Forum Rules. Mark Forums Read. Thread Tools. View Public Profile for jim mcnamara. Additionally, idle, user, system, iowait, etc are a measurement with respect to the CPU.

In other words, you can think of iowait as the idle caused by waiting for io. Precisely, iowait is time spent receiving and handling hardware interrupts as a percentage of processor ticks.

IOWait is important because it often is a key metric to know if you're bottlenecked on IO. But absense of iowait does not necessarily mean your application is not bottlenecked on IO. Consider two applications running on a system. But that's just because program 2 is intensive and relatively appear to say nothing about program 1 because all this is from the CPU's point of view. Also, as we are now almost entering , in addition to what others said, the option of simply awesome IO storage devices are affordable, namely SSDs.

SSDs are awesome!!! I found the explanation and examples from this link very useful: What exactly is "iowait"? I will quote a few important sections in case the link goes dead , some of those would be repetitions of what others have said already, but to me at least these were clearer:. The below explains it:. If there is, then the 'iowait' counter is incremented by one.

Let's say that there are two programs running on a CPU. One is a 'dd' program reading from the disk. When the clock interrupt occurs, there will always be a program running in either user mode or system mode.

The full text is worth reading. Here is a mirror of this page , in case it goes down. This usually means that the block devices i. That should also be apparent from the fact that anything you do on the system is still very responsive.

For Linux, there's a similar program called systemtap which provides a similar level of exposure to the kernel and process calls. One example I used when learning DTrace was to compare a cp command to a dd command.

You can see that dd does a lot more reads for the write, while cp does not, mostly because of the buffer size dd uses by default if I'm remembering correctly. We can get the info also on Windows, but it's not so easy to configure to collect the info. The io-wait is calculated with just wait-time for storage device during the period.

Make sure that you don't see the io-wait value on "all" of mpstat. It's an average value. We should sum up the total io-wait values of all CPUs.