On 14.06.16 07:36:08, Heiko Carstens wrote: > On Mon, Jun 13, 2016 at 06:29:14PM +0200, Robert Richter wrote: > > Heiko, > > > > On 09.06.16 11:00:56, Heiko Carstens wrote: > > > However I'm wondering if we shouldn't simply remove at least the s390 > > > specific hwswampler code from the oprofile module. This would still leave > > > the common code timer based sampling mode for oprofile working on s390. > > > > > > It looks like the oprofile user space utility nowadays (since 2012) uses > > > the kernel perf interface instead of the oprofile interface anyway, if > > > present. So the oprofile module itself doesn't seem to have too many users > > > left. > > > > > > Any opinions? > > > > yes, the kernel driver is not necessary for oprofile userland for a > > while now. There is no ongoing development any longer, most patches > > are due to changes in the kernel apis. > > > > So if there is code that needs a larger rework due to other kernel > > changes and there is no user anymore, I am fine with removing the code > > instead of reworking it. I still would just keep existing code as long > > as we can keep it unchanged (some like the lightwight of oprofile, > > esp. in the embedded space). If there is a user of the code, a > > Tested-by would be good for new code changes. > > > > If there are users of the hwswampler, speak up now. Else, let's just > > remove it. > > Ok, so I'll wait a week or so and remove the code if nobody speaks up. Is > it ok for you if I add the patch to the s390 kernel tree? Yes, pass it through your tree. > The patch would only remove s390 specific architecture code. > > I have this pending: > > s390/oprofile: remove hardware sampler support > > Remove hardware sampler support from oprofile module. > > The oprofile user space utilty has been switched to use the kernel > perf interface, for which we also provide hardware sampling support. > > In addition the hardware sampling support is also slightly broken: it > supports only 16 bits for the pid and therefore would generate wrong > results on machines which have a pid >64k. > > Also the pt_regs structure which was passed to oprofile common code > cannot necessarily be used to generate sane backtraces, since the > task(s) in question may run while the samples are fed to oprofile. > So the result would be more or less random. > > However given that the only user space tools switched to the perf > interface already four years ago the hardware sampler code seems to be > unused code, and therefore it should be reasonable to remove it. > > The timer based oprofile support continues to work. > > Signed-off-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx> Acked-by: Robert Richter <rric@xxxxxxxxxx> > > Documentation/kernel-parameters.txt | 2 - > arch/s390/oprofile/Makefile | 1 - > arch/s390/oprofile/hwsampler.c | 1178 -------------------------------- > arch/s390/oprofile/hwsampler.h | 63 -- > arch/s390/oprofile/init.c | 489 ------------- > arch/s390/oprofile/op_counter.h | 21 - > 6 files changed, 1754 deletions(-) Could you send the patch for review anyway? Thanks, -Robert -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
