search for: clock_thread_cputim

...5:50 AM, Thomas Gleixner <tglx at linutronix.de> wrote: > > With the storage array in place it's now trivial to support CLOCK_TAI in > the vdso. Instead of extending the array to accomodate CLOCK_TAI, make use > of the fact that: > > - CLOCK ids are set in stone > - CLOCK_THREAD_CPUTIME is never going to be supported in the VDSO so > the array slot 3 is unused > - CLOCK_TAI is id 11 which results in 3 when masked with 0x3 > > Add the mask to the basetime array lookup and set up the CLOCK_TAI base > time in update_vsyscall(). That?s... horrible. In an amazing wa...

...5:50 AM, Thomas Gleixner <tglx at linutronix.de> wrote: > > With the storage array in place it's now trivial to support CLOCK_TAI in > the vdso. Instead of extending the array to accomodate CLOCK_TAI, make use > of the fact that: > > - CLOCK ids are set in stone > - CLOCK_THREAD_CPUTIME is never going to be supported in the VDSO so > the array slot 3 is unused > - CLOCK_TAI is id 11 which results in 3 when masked with 0x3 > > Add the mask to the basetime array lookup and set up the CLOCK_TAI base > time in update_vsyscall(). That?s... horrible. In an amazing wa...

With the storage array in place it's now trivial to support CLOCK_TAI in the vdso. Instead of extending the array to accomodate CLOCK_TAI, make use of the fact that: - CLOCK ids are set in stone - CLOCK_THREAD_CPUTIME is never going to be supported in the VDSO so the array slot 3 is unused - CLOCK_TAI is id 11 which results in 3 when masked with 0x3 Add the mask to the basetime array lookup and set up the CLOCK_TAI base time in update_vsyscall(). The performance impact of the mask operation is within the...

...t linutronix.de> wrote: > > > > With the storage array in place it's now trivial to support CLOCK_TAI in > > the vdso. Instead of extending the array to accomodate CLOCK_TAI, make use > > of the fact that: > > > > - CLOCK ids are set in stone > > - CLOCK_THREAD_CPUTIME is never going to be supported in the VDSO so > > the array slot 3 is unused > > - CLOCK_TAI is id 11 which results in 3 when masked with 0x3 > > > > Add the mask to the basetime array lookup and set up the CLOCK_TAI base > > time in update_vsyscall(). > > T...

...rote: >>> >>> With the storage array in place it's now trivial to support CLOCK_TAI in >>> the vdso. Instead of extending the array to accomodate CLOCK_TAI, make use >>> of the fact that: >>> >>> - CLOCK ids are set in stone >>> - CLOCK_THREAD_CPUTIME is never going to be supported in the VDSO so >>> the array slot 3 is unused >>> - CLOCK_TAI is id 11 which results in 3 when masked with 0x3 >>> >>> Add the mask to the basetime array lookup and set up the CLOCK_TAI base >>> time in update_vsyscall()...

Matt attempted to add CLOCK_TAI support to the VDSO clock_gettime() implementation, which extended the clockid switch case and added yet another slightly different copy of the same code. Especially the extended switch case is problematic as the compiler tends to generate a jump table which then requires to use retpolines. If jump tables are disabled it adds yet another conditional to the existing

Matt attempted to add CLOCK_TAI support to the VDSO clock_gettime() implementation, which extended the clockid switch case and added yet another slightly different copy of the same code. Especially the extended switch case is problematic as the compiler tends to generate a jump table which then requires to use retpolines. If jump tables are disabled it adds yet another conditional to the existing