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On 07.07.2016 20:47, David Smith wrote: > On 07/06/2016 07:29 AM, Alexander Lochmann wrote: >> So. Let me start. >> First of all, I extracted the patches properly, and attached the files. >> (Btw, I found a third bug. :) ) >> FYI, I just fixed the bugs for the kernel versions I'm dealing with, >> because I don't know which other versions are affected as well. > > The problem you are trying to fix in your patch "[PATCH 1/3] Definition > of cputime_to_usecs in Linux kernel 3.0 is broken" is interesting. I > don't think you've got quite the right solution. Testing for a kernel > version here works for you, but really isn't a general solution - > depending on arch there could be a kernel in that range with a > reasonable cputime_to_usecs(). I see. :-/ Lesson learned. > > ==== > diff --git a/tapset/linux/task_time.stp b/tapset/linux/task_time.stp > index f86f984..f3c276c 100644 > --- a/tapset/linux/task_time.stp > +++ b/tapset/linux/task_time.stp > @@ -27,8 +27,12 @@ > * Yet note some kernels (RHEL6) may already have both... */ > #if defined(cputime_to_usecs) > #if !defined(cputime_to_msecs) > +#if LINUX_VERSION_CODE <= KERNEL_VERSION(3,0,200) && LINUX_VERSION_CODE >> = KERNEL_VERSION(3,0,0) > +#define cputime_to_msecs(__ct) _stp_div64(NULL, > ({cputime_to_usecs(__ct)}), 1000ULL) > +#else > #define cputime_to_msecs(__ct) _stp_div64(NULL, > cputime_to_usecs(__ct), 1000ULL) > #endif > +#endif > > /* Kernels before 2.6.37 have cputime_to_msecs, but not usecs. */ > #elif defined(cputime_to_msecs) > ==== > > I've got a couple of thoughts here: > > - I wonder if we just couldn't always use your workaround (along with a > comment about why we're doing that). Why not? :) Since the kernel and every module of course is compiled with -O3 (or -O2?), it shouldn't make any difference in the resulting assembler code. > > - Here's an untested workaround idea that might work for all kernels: > > #define cputime_to_msecs(__ct) \ > ({ \ > unsigned long __usecs = cputime_to_usecs(__ct); \ > _stp_div64(NULL, __usecs, 1000ULL); \ > }) > And so does this version. The compiler should be smart enough to recognize __usecs is a local variable, and thus could be stored in a register. - Alex -- Technische Universität Dortmund Alexander Lochmann PGP key: 0xBC3EF6FD Otto-Hahn-Str. 16 phone: +49.231.7556141 D-44227 Dortmund fax: +49.231.7556116 http://ess.cs.tu-dortmund.de/Staff/al
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