On 22/11/2007, Raj Mathur <[EMAIL PROTECTED]> wrote: [snip] > So to sum up: > > Times when the CPU is executing user code is counted in %user. > Times when the CPU is executing a system call (or running any other > kernel code) is counted in %system. > Times when the CPU is waiting for some I/O to complete is counted > in %iowait.
I'm not sure I understand this. When a process requests I/O, it is blocked (or removed from ready queue) and CPU moves on to execute next process in the ready-to-run-queue. When the I/O completes, an event wakes up the blocked process(es). A process may be waiting for its I/O while CPU executing some user code. Does this time counted in %user or %iowait? Times when the CPU is doing nothing is counted in %idle. > > Since the CPU must be doing one of these things at any time, the sum of > these percentages will always be 100. [snip] If %user and %iowait overlap, then why is the sum 100? Or, is %iowait the time when there are no processes in ready-queue because all of them are waiting for I/O? I think that is idle time and not iowait time. - Kazim Zaidi Blog: http://tuxplayground.blogspot.com _______________________________________________ ilugd mailinglist -- ilugd@lists.linux-delhi.org http://frodo.hserus.net/mailman/listinfo/ilugd Next Event: http://freed.in - February 22/23, 2008 Archives at: http://news.gmane.org/gmane.user-groups.linux.delhi http://www.mail-archive.com/ilugd@lists.linux-delhi.org/
