Re: 70,000 TLB shootdown IPIs per second

[Chuck Silvers <chuq%chuq.com@localhost>]

On Wed, Dec 05, 2012 at 12:56:27PM -0500, Thor Lancelot Simon wrote:
> On Wed, Dec 05, 2012 at 08:29:23AM -0800, Chuck Silvers wrote:
> > 
> > 
> > and the top few entries from that with a portion of your dd test are:
...

dtrace outputs counts with the smallest numbers first,
so the most interesting ones are at the bottom:


              netbsd`pmap_update+0x3b
              netbsd`ubc_release+0x26a
              netbsd`ubc_uiomove+0x113
              netbsd`ffs_write+0x2c5
              netbsd`VOP_WRITE+0x37
              netbsd`vn_write+0xf9
              netbsd`dofilewrite+0x7d
              netbsd`sys_write+0x62
              netbsd`syscall+0x94
              netbsd`0xffffffff801006a1
           685211



the similar entry involving ubc_alloc() is a red herring...
I counted calls to pmap_tlb_shootnow(), but that doesn't always send an IPI.
x86_ipi() would have been a better choice.

it would be best if you gathered this info on your system,
to make sure I'm seeing the same thing you are.

-Chuck