> -----Original Message----- > From: John Garry <[email protected]> > Sent: 2020年5月12日 18:13 > To: Joakim Zhang <[email protected]>; [email protected]; > [email protected]; [email protected]; [email protected]; > [email protected]; [email protected]; > [email protected] > Cc: [email protected]; [email protected]; [email protected]; > Linuxarm <[email protected]>; [email protected]; > Zhangshaokun <[email protected]>; [email protected]; > [email protected] > Subject: Re: [PATCH RFC v3 00/12] perf pmu-events: Support event aliasing for > system PMUs > > > > I have an aside question, do you have any idea? Thanks a lot! > > > > For DDR PMU, I want to add bandwidth usage metric, but it depends on DDR > controller clock frequency. > > For example, we have i.MX8MM LPDDR4 board which DDR controller clock is > 800MHZ, and i.MX8MM DDR4 board which DDR controller is 600MHZ, but the > SoC is the same. > > > > So they can share all JSON metrics with identifier "i.mx8mm", except > bandwidth metric. > > what is the bandwidth metric? how is it supposed to be calculated?
Something like below to calculate bandwidth usage: i.MX8MM LPDDR4 board: ((read-cycles + write-cycles) * 4 * 4 / duration_time) / (800 * 1000000 * 4 * 4) i.MX8MM DDR4 board: ((read-cycles + write-cycles) * 4 * 4 / duration_time) / (600 * 1000000 * 4 * 4) So this should not be Soc specific, it is board specific, I don't know how to implement it from metric. > If I add separate JOSN metrics files for identifier "i.mx8mm-lpddr4" and > identifier "i.mx8mm-ddr4", then it's going to be very redundant, since most > metrics are same just the identifier is different. > > > > Do you know how perf tool handle such case? > > jirka is supporting user-defined metric here: > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.ker > nel.org%2Flkml%2F20200511205307.3107775-1-jolsa%40kernel.org%2F& > data=02%7C01%7Cqiangqing.zhang%40nxp.com%7Cbbd26d737cf44896ed360 > 8d7f65d33ad%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C637248 > 752464922384&sdata=wGqQ4%2B6rejJYrDj0SzeGJn09r660QIzOvRy0DCw > EGVQ%3D&reserved=0 > > So maybe you can use that somehow with separate scripts. Thanks for your hint, I will research it to see if it is possible. Best Regards, Joakim Zhang > Thanks, > John
