[RFC][PATCH 2/2] uprobes: single-step out of line

[Jim Keniston]

This patch enhances uprobes to use "single-stepping out of line"
(SSOL) to avoid probe misses in multithreaded applications.  SSOL also
reduces probe overhead by 25-30%.

This patch creates a 1-page VM area in the probed process for SSOL.
This implementation creates the SSOL area only for processes that
are actually probed.  An older implementation, which preallocates
a SSOL area at exec time, can be resurrected if there's interest.
In the current implementation, the size of the SSOL area is fixed
at 1 page.  Slots in the SSOL area are recycled, as necessary, on a
least-recently-used basis.

Comments welcome.

Jim Keniston
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 2-uprobes-ssol.patch
Type: text/x-patch
Size: 25203 bytes
Desc: not available
URL: <http://sourceware.org/pipermail/systemtap/attachments/20070420/75c82211/attachment.bin>