On Thu, Nov 19, 2009 at 2:49 AM, Mike Christie <micha...@cs.wisc.edu> wrote: > Erez Zilber wrote: >> open-iscsi sends nop-outs to the target. If the target responds quick >> enough, we don't get a timeout. I'd like to know (for internal debug >> purposes) how many times the ping timer almost expired. This sounds >> like a useful feature also for other open-iscsi developers/users. >> >> I was thinking about adding the following mechanism: >> >> 1. Add an array of some length to store long nop-outs. Protect it with >> some lock. >> 2. If a nop-in (as a response to nop-out) was received after >= 0.7 * >> ping_to (or 0.8 or whatever), add some info about it to the array >> (when was the nop-out sent, how much time until we got a nop-in etc). >> 3. The array should be used in a cyclic way - when it gets full, >> overwrite the 1st entry. >> 4. We can dump the info from the array from time to time or the user >> may use iscsiadm to do that. When this is done, we can delete the >> contents of the array. >> > > What info did you want to store?
The following info: 1. The exact time when the nop-out was sent. 2. How much time until we got the nop-in. > > > What about some perf counters for it? Add a counter for if a ping took > a-b secs, b-c secs, and c-d secs. This is problematic because: 1. You can set your ping timeout to X. According to your suggestion, we will need to have the following counters: a. < 0.2*X b. 0.2*X - 0.4*X c. 0.4*X - 0.6*X d. 0.6*X - 0.8*X e. 0.8*X - X This means that the names of the counters will change according to the value of X. You may have different values of X for different connections which makes this more problematic. 2. If you have the array that I suggest instead of these counters and you see that on 17:45:07 you had a long ping (that did not time out), you can check what happened on that time in your target. This may be very helpful. Erez -- You received this message because you are subscribed to the Google Groups "open-iscsi" group. To post to this group, send email to open-is...@googlegroups.com. To unsubscribe from this group, send email to open-iscsi+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/open-iscsi?hl=.