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SubjectRe: [PATCH] s390/oprofile: Remove deprecated create_workqueue
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@de.ibm.com>

Acked-by: Robert Richter <rric@kernel.org>

>
> 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

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