9 Dec
2024
9 Dec
'24
12:12 p.m.
On Mon, Dec 09, 2024 at 01:04:43PM +0100, Valentin Schneider wrote:
But I wonder what exactly was the original scenario encountered by Valentin. I mean, if TLB entry invalidations were necessary to sync changes to kernel text after flipping a static branch, then it might be less overhead to make a list of affected pages and call INVLPG on them.
No; TLB is not involved with text patching (on x86).
Valentin, do you happen to know?
So from my experimentation (hackbench + kernel compilation on housekeeping CPUs, dummy while(1) userspace loop on isolated CPUs), the TLB flushes only occurred from vunmap() - mainly from all the hackbench threads coming and going.
Right, we have virtually mapped stacks.