Hi, On 31/08/18 15:22, Peter Ujfalusi wrote: > Hi, > > On 2018-08-31 16:41, Seraj Mohammed wrote: >>> Can I still use: >>> echo "" > /sys/module/dmatest/parameters/channel >>> >>> to stop dmatest to run on the specific channel(s) or do I need to reboot >>> the machine to do so? >> >> is this behavior documented somewhere? or did you discover this from your >> experience with using the module? > > If the channels is "" then it is not set. We can change the channels > currently and there is no difference between selecting a channel or > selecting none. > >> The short answer to your question is no, with this change you cannot stop >> a test by echoing an empty string to the channel parameter, you will either >> have to run the test, or reboot the machine. >> >> Setting the channel parameter to an empty string will request all >> channels up to "max_channels" parameter value. > > Yes, and it is very useful. What would be even more useful is if via the > channel I could select the starting channel from where the max_channels > will start... Since this patch already allows you to specifically select which channels to run on, i don't see the benefit in allocating channels using ranges. >> This is because with this >> change, editing the channel parameter will invoke the process of allocating >> a thread for the specified channel and storing that thread in a thread >> list, after that, setting run to 1 will simply iterate through the thread >> list and start all pending threads. > > We have automated regression tests via dmatest's memcpy, it does changes > parameters between runs to gather the data for different transfer sizes, > runs in selected channels and runs also with different max_channels. > > It is a regression if we need to reboot between every test to change > parameters, channels, etc. Once you have successfully completed a test, you don't need to reboot to start a new one with different parameters. > - Péter > > Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. > Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki >
