Messages in this thread | ![/](/images/icornerl.gif) | | Date | Fri, 09 Apr 2010 17:58:05 -0400 | From | Masami Hiramatsu <> | Subject | Re: [PATCH 0/9] jump label v6 |
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Jason Baron wrote: > On Fri, Apr 09, 2010 at 04:36:24PM -0400, Masami Hiramatsu wrote: >> Hi Jason, >> >> Jason Baron wrote: >>> Hi, >>> >>> Refresh of jump labeling patches aginst -tip tree. For bacground see: >>> http://marc.info/?l=linux-kernel&m=125858436505941&w=2 >>> >>> I believe I've addressed all the reviews from v5. >>> >>> Changes in v6: >>> >>> * I've moved Steve Rostedt's 'ftrace_dyn_arch_init()' to alternative.c to >>> put it into a common area for used by both ftrace and jump labels. By >>> default we put a 'jmp 5' in the nop slot. Then, when we detect the best >>> runtime no-op we patch over the 'jmp 5' with the appropriate nop. >>> >>> * build time sort of the jump label table. The jump label table is more >>> optimally accessed if the entries are continguous. Sorting the table >>> accomplishes this. Do the sort at build-time. Adds a '-j' option to >>> 'modpost' which replaces the vmlinux, with a sorted jump label section vmlinux. >>> I've tested this on x86 with relocatable and it works fine there as well. Note >>> that I have not sorted the jump label table in modules. This is b/c the jump >>> label names can be exported by the core kernel, and thus I don't have them >>> available at buildtime. This could be solved by either finding the correct >>> ones in the vmlinux, or by embedding the name of the jump label in the module >>> tables (and not just a pointer), but the module tables tend to be smaller, and >>> thus there is less value to this kind of change anyway. The kernel continues to >>> do the sort, just in case, but at least for the vmlinux, this is just a >>> verfication b/c the jump label table has already been sorted. >>> >>> * added jump_label_text_reserved(), so that other routines that want to patch >>> the code, can first verify that they are not stomping on jump label addresses. >> >> Good!:-) >> So now, it might be a good time to integrate those text_reserved() functions. >> >> BTW, how many jumps would you expect modifying at once? >> Since the text_poke_smp() uses stop_machine() for each modifying text, >> I found that it can cause a delay issue if it is called so many times... >> (e.g. a systemtap testcase sets ~5000 probes at once) >> >> Thank you, >> > > I'm counting 934 jump label locations in the vmlinux, i have compiled, > 675 of them being 'kmalloc'. Batch mode for text_poke_smp()?
Yeah:) I'm now trying to make it with updating kprobes.
Thank you,
-- Masami Hiramatsu e-mail: mhiramat@redhat.com
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