G
George Potemkin
Guest
@TheMadDBA Having a process trying to sleep for 2 seconds and ending up taking 4 seconds isn't that weird to me in that situation. All sampling intervals of Activity screens in promon are exactly 2 seconds: "Total" values divided by "Per Sec" values are always 2 sec. It's because the sampling in promon creates a copy of activity statistics data stored wholly in shared memory. But some promon screens ("Status" as well "Activity") do read db blocks from the disks. 07/16/15 Activity: Summary 18:25:41 07/16/15 18:25 to 07/16/15 18:25 (2 sec) In this example 18:25:41 is NOT the end of sampling interval. It's the time when promon displays statistics. For example, the "Activity: Summary" screen displays the activity statistics (Commits, Reads, Writes) from shared memory as well as from database blocks (Free blocks, RM chain). Sometimes the difference between timestamps of promon screens can be the meaningful information that might help to identify a bottleneck. I often saw the delays when promon dysplays "Status: Buffer Lock Queue". "Activity: I/O Operations by File" were not on my radar in past.
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