Re: [PATCH] x86/mm: Don't flush the TLB on #WP pmd fixups

[Ingo Molnar]

* Ingo Molnar <mingo@xxxxxxxxxx> wrote:

> * Ingo Molnar <mingo@xxxxxxxxxx> wrote:
> 
> > numa/core profile:
> > 
> >     95.66%  perf-1201.map     [.] 0x00007fe4ad1c8fc7                 
> >      1.70%  libjvm.so         [.] 0x0000000000381581                 
> >      0.59%  [vdso]            [.] 0x0000000000000607                 
> >      0.19%  [kernel]          [k] do_raw_spin_lock                   
> >      0.11%  [kernel]          [k] generic_smp_call_function_interrupt
> >      0.11%  [kernel]          [k] timekeeping_get_ns.constprop.7     
> >      0.08%  [kernel]          [k] ktime_get                          
> >      0.06%  [kernel]          [k] get_cycles                         
> >      0.05%  [kernel]          [k] __native_flush_tlb                 
> >      0.05%  [kernel]          [k] rep_nop                            
> >      0.04%  perf              [.] add_hist_entry.isra.9              
> >      0.04%  [kernel]          [k] rcu_check_callbacks                
> >      0.04%  [kernel]          [k] ktime_get_update_offsets           
> >      0.04%  libc-2.15.so      [.] __strcmp_sse2                      
> > 
> > No page fault overhead (see the page fault rate further below) 
> > - the NUMA scanning overhead shows up only through some mild 
> > TLB flush activity (which I'll fix btw).
> 
> The patch attached below should get rid of that mild TLB 
> flushing activity as well.

This has further increased SPECjbb from 203k/sec to 207k/sec, 
i.e. it's now 5% faster than mainline - THP enabled.

The profile is now totally flat even during a full 32-WH SPECjbb 
run, with the highest overhead entries left all related to timer 
IRQ processing or profiling. That is on a system that should be 
very close to yours.

Thanks,

	Ingo
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