Re: Using sched_clock for mmio-trace

2007-02-18 Thread Andi Kleen
On Sat, Feb 17, 2007 at 04:19:58PM +0100, Thomas Gleixner wrote: > On Sat, 2007-02-17 at 15:56 +0100, Andi Kleen wrote: > > > This is one of the reasons why we don't just use good old > > > do_gettimeofday(), since it takes locks and can lead to lock recursion > > > if parts of itself are probed. >

Re: Using sched_clock for mmio-trace

2007-02-17 Thread Thomas Gleixner
On Sat, 2007-02-17 at 15:56 +0100, Andi Kleen wrote: > > This is one of the reasons why we don't just use good old > > do_gettimeofday(), since it takes locks and can lead to lock recursion > > if parts of itself are probed. > > do_gettimeofday doesn't take locks. > > Only restriction is that you

Re: Using sched_clock for mmio-trace

2007-02-17 Thread Andi Kleen
> This is one of the reasons why we don't just use good old > do_gettimeofday(), since it takes locks and can lead to lock recursion > if parts of itself are probed. do_gettimeofday doesn't take locks. Only restriction is that you can't single step it with long pauses between instructions. -And

Re: Using sched_clock for mmio-trace

2007-02-16 Thread Jeff Muizelaar
On Fri, Feb 16, 2007 at 02:47:45PM -0800, Daniel Walker wrote: > > > Gets pretty ugly .. The clocksource interface already has a positive > > > rating to describe the "best" clocks in the system, which is used to > > > return the "best" clock .. Where the maintainers of the system give each > > > c

Re: Using sched_clock for mmio-trace

2007-02-16 Thread Daniel Walker
On Fri, 2007-02-16 at 17:10 -0500, Jeff Muizelaar wrote: > > I still meant for _with_features to have same semantics so calling: > > clocksource_get_clock_with_features(CLOCKSOURCE_PM_UNAFFECTED|CLOCKSOURCE_STABLE > |CLOCKSOURC_ATOMIC|CLOCKSOURCE_64BITS|CLOCKSOURCE_CONTINUOUS); > > would be eq

Re: Using sched_clock for mmio-trace

2007-02-16 Thread Jeff Muizelaar
On Fri, Feb 16, 2007 at 01:06:19PM -0800, Daniel Walker wrote: > On Fri, 2007-02-16 at 14:34 -0500, Jeff Muizelaar wrote: > > It think it would be better if you had sometime like > > 'clocksource_get_clock_with_features()' that took flags describing the > > needed characteristics instead of the unw

Re: Using sched_clock for mmio-trace

2007-02-16 Thread Frank Ch. Eigler
Hi - On Fri, Feb 16, 2007 at 09:03:23PM +0100, Andi Kleen wrote: > > We in systemtap land have the same problem, and so far made do with > > slightly postprocessed per-cpu TSC values. > > 90+% likely you're not solving your problem correctly this way. Yes, it was done as a last resort. We need

Re: Using sched_clock for mmio-trace

2007-02-16 Thread Daniel Walker
On Fri, 2007-02-16 at 14:34 -0500, Jeff Muizelaar wrote: > On Fri, Feb 16, 2007 at 10:28:50AM -0800, Daniel Walker wrote: > > On Fri, 2007-02-16 at 13:10 -0500, Jeff Muizelaar wrote: > > > On Fri, Feb 16, 2007 at 09:45:21AM -0800, Daniel Walker wrote: > > > > I've been working on a patch set (below

Re: Using sched_clock for mmio-trace

2007-02-16 Thread Jeff Muizelaar
On Fri, Feb 16, 2007 at 10:44:15AM -0800, Randy Dunlap wrote: > On Fri, 16 Feb 2007 13:30:14 -0500 Jeff Muizelaar wrote: > > > On Fri, Feb 16, 2007 at 11:30:56AM -0500, Frank Ch. Eigler wrote: > > > Jeff Muizelaar <[EMAIL PROTECTED]> writes: > > > > > > > I've built a tool with the goal of loggin

Re: Using sched_clock for mmio-trace

2007-02-16 Thread Jeff Muizelaar
On Fri, Feb 16, 2007 at 09:02:44PM +0100, Andi Kleen wrote: > Jeff Muizelaar <[EMAIL PROTECTED]> writes: > > > > The question is, what api should I be using? I need something that can > > be called from inside interrupt handlers, and obviously the more > > accurate and the lower the overhead the b

Re: Using sched_clock for mmio-trace

2007-02-16 Thread Jeff Muizelaar
On Fri, Feb 16, 2007 at 10:28:50AM -0800, Daniel Walker wrote: > On Fri, 2007-02-16 at 13:10 -0500, Jeff Muizelaar wrote: > > On Fri, Feb 16, 2007 at 09:45:21AM -0800, Daniel Walker wrote: > > > I've been working on a patch set (below), to expose the clocksources > > > used by generic time to multi

Re: Using sched_clock for mmio-trace

2007-02-16 Thread Andi Kleen
[EMAIL PROTECTED] (Frank Ch. Eigler) writes: > > We in systemtap land have the same problem, and so far made do with > slightly postprocessed per-cpu TSC values. 90+% likely you're not solving your problem correctly this way. -Andi - To unsubscribe from this list: send the line "unsubscribe linu

Re: Using sched_clock for mmio-trace

2007-02-16 Thread Andi Kleen
Jeff Muizelaar <[EMAIL PROTECTED]> writes: > > The question is, what api should I be using? I need something that can > be called from inside interrupt handlers, and obviously the more > accurate and the lower the overhead the better. Use do_gettimeofday(). sched_clock() is not for general use an

Re: Using sched_clock for mmio-trace

2007-02-16 Thread Randy Dunlap
On Fri, 16 Feb 2007 13:30:14 -0500 Jeff Muizelaar wrote: > On Fri, Feb 16, 2007 at 11:30:56AM -0500, Frank Ch. Eigler wrote: > > Jeff Muizelaar <[EMAIL PROTECTED]> writes: > > > > > I've built a tool with the goal of logging mmio writes and reads by > > > device drivers. See http://nouveau.freede

Re: Using sched_clock for mmio-trace

2007-02-16 Thread Daniel Walker
On Fri, 2007-02-16 at 13:10 -0500, Jeff Muizelaar wrote: > On Fri, Feb 16, 2007 at 09:45:21AM -0800, Daniel Walker wrote: > > I've been working on a patch set (below), to expose the clocksources > > used by generic time to multiple users . It would allow timestamps from > > different clocks in a ge

Re: Using sched_clock for mmio-trace

2007-02-16 Thread Jeff Muizelaar
On Fri, Feb 16, 2007 at 11:30:56AM -0500, Frank Ch. Eigler wrote: > Jeff Muizelaar <[EMAIL PROTECTED]> writes: > > > I've built a tool with the goal of logging mmio writes and reads by > > device drivers. See http://nouveau.freedesktop.org/wiki/MmioTrace. > > FWIW, this is exactly a type of add-o

Re: Using sched_clock for mmio-trace

2007-02-16 Thread Jeff Muizelaar
On Fri, Feb 16, 2007 at 09:45:21AM -0800, Daniel Walker wrote: > I've been working on a patch set (below), to expose the clocksources > used by generic time to multiple users . It would allow timestamps from > different clocks in a generic way. It's not merged, but I'd appreciate > any input either

Re: Using sched_clock for mmio-trace

2007-02-16 Thread Daniel Walker
On Fri, 2007-02-16 at 11:30 -0500, Frank Ch. Eigler wrote: > Jeff Muizelaar <[EMAIL PROTECTED]> writes: > > > I've built a tool with the goal of logging mmio writes and reads by > > device drivers. See http://nouveau.freedesktop.org/wiki/MmioTrace. > > FWIW, this is exactly a type of add-on trace

Re: Using sched_clock for mmio-trace

2007-02-16 Thread Frank Ch. Eigler
Jeff Muizelaar <[EMAIL PROTECTED]> writes: > I've built a tool with the goal of logging mmio writes and reads by > device drivers. See http://nouveau.freedesktop.org/wiki/MmioTrace. FWIW, this is exactly a type of add-on trace patch that could be mooted by adoption of the ltt/systemtap "marker" f