Messages in this thread | | | Date | Mon, 28 Jan 2008 01:10:10 -0800 | From | Andrew Morton <> | Subject | Re: [RFC] Per-thread getrusage |
| |
On Mon, 28 Jan 2008 10:48:23 +0300 Pavel Emelyanov <xemul@openvz.org> wrote:
> 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? > > > > That's impossible. I explicitly deny namespace creation in case the > CLONE_THREAD is specified. So all threads of a single process always > live in one pid namespace. >
If the code was using find_task_by_vpid() then OK (I guess). But it is looking the tids up in the init_pid_ns. Which I assume means that if it's in a new namespace and is looking up a sibling thread it will simply fail?
Or am I missing something?
| |