* Re: [...] kprobes [minutes] portion 20060406 [not found] <OF450EB249.F3B0B23E-ON88257148.00738621-88257148.0074730E@us.ibm.com> @ 2006-04-06 21:28 ` Frank Ch. Eigler 2006-04-06 22:08 ` Richard J Moore 2006-04-07 8:25 ` Prasanna S Panchamukhi 0 siblings, 2 replies; 4+ messages in thread From: Frank Ch. Eigler @ 2006-04-06 21:28 UTC (permalink / raw) To: Hien Q Nguyen; +Cc: systemtap Hi - On Thu, Apr 06, 2006 at 02:14:46PM -0700, Hien Q Nguyen wrote: > User space probe > Prasanna had prototype that execute the handler in the user space [...] Beyond merely dispatching, it is important to consider what such a handler can do. Would it still be useful if it cannot call into the kernel-side runtime, if it cannot share variables with kernel-space probes? - FChE ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [...] kprobes [minutes] portion 20060406 2006-04-06 21:28 ` [...] kprobes [minutes] portion 20060406 Frank Ch. Eigler @ 2006-04-06 22:08 ` Richard J Moore 2006-04-07 8:25 ` Prasanna S Panchamukhi 1 sibling, 0 replies; 4+ messages in thread From: Richard J Moore @ 2006-04-06 22:08 UTC (permalink / raw) To: Frank Ch. Eigler; +Cc: Hien Q Nguyen, systemtap Unfortunately I missed the discussion. Am I right in deducing that user-space probes as being discussed here are designed or intended as probes for use with an application's perspective? If so, I believe that is wrong or at least only attending to part of the need. For me the real benefit of user-space probes is to provide an extension to a kernel probe that gives it full access to the system. The arguments on lkml put forward by Christoph and Arjan have value when one thinks of a user-probe only serving user-space code and a user-space problem. But we have tools already in place to deal with that. Have we fully appreciated the need when addressing certain system or kernel problems that one needs access to full system resources, which will include user-space code and data. Anyone who works on performance problems (hangs being an extreme example) involving the networking stack will corroborate this need. An more generally anyone that works with a kernel-based server component of a client-server model will also corroborate this need. Richard - - Richard J Moore IBM Advanced Linux Response Team - Linux Technology Centre MOBEX: 264807; Mobile (+44) (0)7739-875237 Office: (+44) (0)1962-817072 "Frank Ch. Eigler" <fche@redhat.co To m> Hien Q Nguyen <nguyhien@us.ibm.com> Sent by: cc systemtap-owner systemtap@sources.redhat.com @sourceware.org bcc Subject 06/04/2006 Re: [...] kprobes [minutes] portion 22:28 20060406 Hi - On Thu, Apr 06, 2006 at 02:14:46PM -0700, Hien Q Nguyen wrote: > User space probe > Prasanna had prototype that execute the handler in the user space [...] Beyond merely dispatching, it is important to consider what such a handler can do. Would it still be useful if it cannot call into the kernel-side runtime, if it cannot share variables with kernel-space probes? - FChE ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [...] kprobes [minutes] portion 20060406 2006-04-06 21:28 ` [...] kprobes [minutes] portion 20060406 Frank Ch. Eigler 2006-04-06 22:08 ` Richard J Moore @ 2006-04-07 8:25 ` Prasanna S Panchamukhi 2006-04-07 8:43 ` Richard J Moore 1 sibling, 1 reply; 4+ messages in thread From: Prasanna S Panchamukhi @ 2006-04-07 8:25 UTC (permalink / raw) To: Frank Ch. Eigler; +Cc: Hien Q Nguyen, systemtap On Thu, Apr 06, 2006 at 05:28:38PM -0400, Frank Ch. Eigler wrote: > Hi - > > On Thu, Apr 06, 2006 at 02:14:46PM -0700, Hien Q Nguyen wrote: > > User space probe > > Prasanna had prototype that execute the handler in the user space [...] > > Beyond merely dispatching, it is important to consider what such a > handler can do. Would it still be useful if it cannot call into the > kernel-side runtime, if it cannot share variables with kernel-space > probes? No. The purpose of prototype was to see how it can be implemented. To my opinion having handler run in user-space does not suit well for system-wide tracing. But that might be one of the alternative approaches to per-process tracing, since ptrace is found to have more performance related problems. Thanks Prasanna -- Thanks & Regards Prasanna S Panchamukhi Linux Technology Center India Software Labs, IBM Bangalore Email: prasanna@in.ibm.com Ph: 91-80-51776329 ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [...] kprobes [minutes] portion 20060406 2006-04-07 8:25 ` Prasanna S Panchamukhi @ 2006-04-07 8:43 ` Richard J Moore 0 siblings, 0 replies; 4+ messages in thread From: Richard J Moore @ 2006-04-07 8:43 UTC (permalink / raw) To: prasanna; +Cc: Frank Ch. Eigler, Hien Q Nguyen, systemtap systemtap-owner@sourceware.org wrote on 07/04/2006 09:25:17: > > On Thu, Apr 06, 2006 at 05:28:38PM -0400, Frank Ch. Eigler wrote: > > Hi - > > > > On Thu, Apr 06, 2006 at 02:14:46PM -0700, Hien Q Nguyen wrote: > > > User space probe > > > Prasanna had prototype that execute the handler in the user space [...] > > > > Beyond merely dispatching, it is important to consider what such a > > handler can do. Would it still be useful if it cannot call into the > > kernel-side runtime, if it cannot share variables with kernel-space > > probes? > > No. The purpose of prototype was to see how it can be implemented. > To my opinion having handler run in user-space does not suit well for > system-wide tracing. But that might be one of the alternative approaches > to per-process tracing, since ptrace is found to have more performance > related problems. > > Agreed, but don't let the creation of per-process probe handlers detract from the argument for a system-wide capabiltiy; that's the real battle-ground. Richard > Thanks > Prasanna > -- > Thanks & Regards > Prasanna S Panchamukhi > Linux Technology Center > India Software Labs, IBM Bangalore > Email: prasanna@in.ibm.com > Ph: 91-80-51776329 ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2006-04-07 8:43 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- [not found] <OF450EB249.F3B0B23E-ON88257148.00738621-88257148.0074730E@us.ibm.com> 2006-04-06 21:28 ` [...] kprobes [minutes] portion 20060406 Frank Ch. Eigler 2006-04-06 22:08 ` Richard J Moore 2006-04-07 8:25 ` Prasanna S Panchamukhi 2006-04-07 8:43 ` Richard J Moore
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