> From: Gabbasov, Andrew > Sent: Monday, February 18, 2013 14:14 > To: Mathieu Desnoyers > Cc: [email protected] > Subject: RE: LTTng: global_dirty_limit symbol lookup failed > > > Hi Andrew, > > > > Commit: > > > > commit b87700e318c27267890cbd6fb5e50b687279131b > > Author: Andrew Gabbasov <[email protected]> > > Date: Mon Dec 10 11:14:52 2012 -0500 > > > > Add new kernel probes instrumentation > > > > Add kernel probes for btrfs, compaction, ext4, printk, random, rcu, > > regmap, rpm, sunrpc, workqueue, writeback. > > > > Signed-off-by: Andrew Gabbasov <[email protected]> > > Signed-off-by: Mathieu Desnoyers <[email protected]> > > > > has 2 issues: > > > > 1) it implements a wrapper around global_dirty_limit() in probes/. All > > wrappers should be in /wrapper/, without exception, otherwise the > > code will quickly become unmaintainable (we need to know what > > wrappers we can eventually remove if we remove support for older > > kernels in the future, and we need to be aware of those wrappers for > > complete testing coverage). I have no problem with having a > > probes/Makefile using a relative path (e.g. ../wrapper/somefile.o) as > > input if needed. > > > > 2) It fills my dmesg log output with: > > "LTTng: global_dirty_limit symbol lookup failed." > > messages. .config follows. > > > > Can you look into those issues ? > > > > Thanks, > > > > Mathieu > > Hi Mathieu, > > Sorry for a late response. > > I'm sending a separate e-mail with the patch to fix these issues. Here are > some details: > > 1) I moved the wrapper to a separate file wrapper/writeback.h. Since it is > supposed to be used > in writeback probe only, I think, using static variable will be harmless. > > 2) Since global_dirty_limit is not a function, but a global variable, its > address is available > to kallsyms lookup only if CONFIG_KALLSYMS_ALL is set. In order not to > introduce wrapper > related checks of this config into tracepoint definition include file, I > decided not to exclude > separate tracepoints in case of this config absence, but to omit the whole > probe from > building. So, writeback probe will be available only if CONFIG_KALLSYMS_ALL > is set. > > 3) Additional issue that I noticed: in case of CONFIG_THUMB2_KERNEL setting > for ARM, > kallsyms_lookup_funcptr modifies the address found for the symbol. In order > to avoid > it for data addresses, I introduced a new kallsyms_lookup_dataptr function, > that does not > do any address modifications. And this new function is used for > global_dirty_limit wrapper. > > Thanks. > > Best regards, > Andrew
Hi Mathieu, Any thoughts on these changes? Do you need anything else regarding it (the patch itself was sent separately on Feb 18, 2013, with a subject "[PATCH lttng-modules] Clean up using global_dirty_limit wrapper for writeback probe"). Thanks. Best regards, Andrew _______________________________________________ lttng-dev mailing list [email protected] http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
