![]() | |||||||||||||
Messages in this thread |
On Mon, Mar 27, 2006 at 09:37:48AM +0200, Arjan van de Ven wrote: > On Mon, 2006-03-27 at 12:24 +0530, Prasanna S Panchamukhi wrote: > > > - Low overhead and user can have thousands of active probes on the > > system and detect any instance when the probe was hit including > > probes on shared library etc. > > I suspect this is the only reason for doing it inside the kernel; > anything else still really shouts "do it in userspace via ptrace" to me. > Other reasons would be: - to view some privilaged data, such as system regs while you are debugging in user-space - to view many arbitrary process address-space that use a common set of modules - user or kernel space > > > =========================================================== > > LOCAL PROBES(PER PROCESS) VS GLOBAL PROBES(EXECUTABLE FILE) > > =========================================================== > > > > - All processes take a trap since the same executable file > > gets mapped into different address_space. > > is that true for breakpoints inserted after start? Yes, insertion of the breakpoint happens at the physical page level and it gets written back to the disc. > The reason I ask because... what if half the processed took a COW on the > page with the instruction you want to trap on. Are you going to edit all > those COW'd pages? The current prototype does not insert probes on COW pages, but yes eventually we will provide probes insertions on COW'd pages feature too. Thanks Prasanna -- Prasanna S Panchamukhi Linux Technology Center India Software Labs, IBM Bangalore Email: prasanna@in.ibm.com Ph: 91-80-51776329 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
| Last update: 2006-03-27 12:02 [from the cache] ©2003-2008 | |||||||||||||