Messages in this thread | | | From | Sripathi Kodi <> | Subject | Re: [RFC] Per-thread getrusage | Date | Mon, 28 Jan 2008 13:54:12 +0530 |
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Hi Andrew,
On Monday 28 January 2008 11:22, Andrew Morton wrote: > On Thu, 17 Jan 2008 13:57:05 +0530 Vinay Sridhar <vinay@linux.vnet.ibm.com> wrote: > > Hi All, > > > > Last year, there was discussion about per-thread getrusage by > > adding RUSAGE_THREAD flag to getrusage(). Please refer to the > > thread http://lkml.org/lkml/2007/4/4/308. Ulrich had suggested that > > we should design a better user-space API. Specifically, we need a > > pthread_getrusage interface in the thread library, which accepts > > pthread_t, converts pthread_t into the corresponding tid and passes > > it down to the syscall. > > > > There are two ways to implement this in the kernel: > > 1) Introduce an additional parameter 'tid' to sys_getrusage() and > > put code in glibc to handle getrusage() and pthread_getrusage() > > calls correctly. > > 2) Introduce a new system call to handle pthread_getrusage() and > > leave sys_getrusage() untouched. > > > > We implemented the second idea above, simply because it avoids > > touching any existing code. We have implemented a new syscall, > > thread_getrusage() and we have exposed pthread_getrusage() API to > > applications. > > > > Could you please share your thoughts on this? Does the approach > > look alright? The code is hardly complete. It is just a prototype > > that works on IA32 at the moment. > > > > ... > > > > +asmlinkage long sys_thread_getrusage(int tid, struct rusage __user > > *ru); > > What happens if `tid' refers to a thread in a different pid > namespace?
The code was only meant to be a base for discussions. It surely needs work. Our idea for the final version was to be able to read a thread's rusage from another thread strictly within the same process. The idea came from applications that need a cost enforcement mechanism. Having a mechanism for a thread to read it's own usage is essential. If there is a way to read other threads' rusage, it is even better.
Does Roland's patch (http://lkml.org/lkml/2008/1/18/589) look good to go in, provided Ulrich's comment (http://lkml.org/lkml/2008/1/19/15) is addressed?
Thanks, Sripathi.
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