On Mon, 2007-03-26 at 09:58 -0400, Alan D. Brunelle wrote: > Ming Zhang wrote: > > On Sun, 2007-03-25 at 23:51 -0400, Alan D. Brunelle wrote: > > > >> Ming Zhang wrote: > >> > >>> from btt user guide > >>> > >>> "Q2Q which measures the time between queue traces in the system. > >>> This provides some idea as to how quickly IOs are being handed to > >>> the block IO layer." > >>> > >>> does this mean the time between queuing N request and N > >>> +1 request? > >>> > >>> > >> Hi Ming - > >> > >> This is the average time between the Q traces being logged. We take the > >> difference between each succeeding Q trace, and divide the sum by the > >> total. > >> > > > > so like block layer idle indicator. > > Not quite - the block layer %util value indicates how much the > underlying device (driver) has active commands. Q2Q is more of a measure > of upper-level activity - application & file system & VM (page cache). > It indicates how quickly commands are being submitted to the block IO layer. >
sorry, after hit the send button, i realized my fault. yes, it is a incoming system idleness indicator. like a incoming rate. > > > maybe a similar D2D will be a nice > > device indicator as well. > > > > This would be an indicator of how quickly lower-layer device drivers are > getting issued IOs. It would be trivial to implement, if you are > interested in it, I can do it... i think this will be interesting when compare with Q2Q to see how block layer smooth/intense the io. > > Alan > > > > > > >> Alan > >> > >>> thanks! > >>> > >>> Ming > >>> > >>> > >>> - > >>> To unsubscribe from this list: send the line "unsubscribe linux-btrace" in > >>> the body of a message to [EMAIL PROTECTED] > >>> More majordomo info at http://vger.kernel.org/majordomo-info.html > >>> > >>> > >> - > >> To unsubscribe from this list: send the line "unsubscribe linux-btrace" in > >> the body of a message to [EMAIL PROTECTED] > >> More majordomo info at http://vger.kernel.org/majordomo-info.html > >> > > > > - > > To unsubscribe from this list: send the line "unsubscribe linux-btrace" in > > the body of a message to [EMAIL PROTECTED] > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > - > To unsubscribe from this list: send the line "unsubscribe linux-btrace" in > the body of a message to [EMAIL PROTECTED] > More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line "unsubscribe linux-btrace" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
