RE: [PATCH] migration: Move bitmap_mutex out of migration_bitmap_clear_dirty()

[Wang, Wei W]

On Thursday, July 8, 2021 12:45 AM, Peter Xu wrote:
> On Wed, Jul 07, 2021 at 12:45:32PM +0000, Wang, Wei W wrote:
> > Btw, what would you think if we change mutex to QemuSpin? It will also 
> > reduce
> the overhead, I think.
> 
> As I replied at the other place, the bottleneck we encountered is the lock 
> taking
> not sleeping, so I'm afraid spinlock will have the same issue. Thanks,

I suspect the overhead you observed might be caused by the syscalls for mutex. 
Per-page syscall might be too much.
If possible, you could have another test of the 3GB guest migration using 
QemuSpin.

Best,
Wei