Messages in this thread | | | Date | Mon, 18 Jan 2010 15:06:45 +0200 | From | Avi Kivity <> | Subject | Re: [RFC] [PATCH 1/7] User Space Breakpoint Assistance Layer (UBP) |
| |
On 01/18/2010 02:57 PM, Pekka Enberg wrote: > On 01/18/2010 02:51 PM, Pekka Enberg wrote: >>> And how many probes do we expected to be live at the same time in >>> real-world scenarios? I guess Avi's "one million" is more than enough? > > Avi Kivity kirjoitti: >> I don't think a user will ever come close to a million, but we can >> expect some inflation from inlined functions (I don't know if uprobes >> replicates such probes, but if it doesn't, it should). > > Right. I guess we're looking at few megabytes of the address space for > normal scenarios which doesn't seem too excessive. > > However, as Peter pointed out, the bigger problem is that now we're > opening the door for other features to steal chunks of the address > space. And I think it's a legitimate worry that it's going to cause > problems for 32-bit in the future. > > I don't like the idea but if the performance benefits are real (are > they?), maybe it's a worthwhile trade-off. Dunno.
If uprobes can trace to buffer memory in the process address space, I think the win can be dramatic. Incidentally it will require injecting even more vmas into a process.
Basically it means very low cost tracing, like the kernel tracers.
-- error compiling committee.c: too many arguments to function
| |