Re: [RFC patch 02/15] x86/entry: Remove _TIF_NOHZ from _TIF_WORK_SYSCALL_ENTRY

2019-09-23 Thread Thomas Gleixner
On Fri, 20 Sep 2019, Andy Lutomirski wrote: > On Thu, Sep 19, 2019 at 8:09 AM Thomas Gleixner wrote: > > > > Evaluating _TIF_NOHZ to decide whether to use the slow syscall entry path > > is not only pointless, it's actually counterproductive: > > > > 1) Context tracking code is invoked unconditi

Re: [RFC patch 02/15] x86/entry: Remove _TIF_NOHZ from _TIF_WORK_SYSCALL_ENTRY

2019-09-20 Thread Andy Lutomirski
On Thu, Sep 19, 2019 at 8:09 AM Thomas Gleixner wrote: > > Evaluating _TIF_NOHZ to decide whether to use the slow syscall entry path > is not only pointless, it's actually counterproductive: > > 1) Context tracking code is invoked unconditionally before that flag is > evaluated. > > 2) If th

[RFC patch 02/15] x86/entry: Remove _TIF_NOHZ from _TIF_WORK_SYSCALL_ENTRY

2019-09-19 Thread Thomas Gleixner
Evaluating _TIF_NOHZ to decide whether to use the slow syscall entry path is not only pointless, it's actually counterproductive: 1) Context tracking code is invoked unconditionally before that flag is evaluated. 2) If the flag is set the slow path is invoked for nothing due to #1 Remove i