Re: [PATCH v3 1/1] swiotlb: Track and report io_tlb_used high water mark in debugfs

[hch@xxxxxx]

On Fri, Apr 07, 2023 at 10:05:26PM +0000, Michael Kelley (LINUX) wrote:
> > Yes, this works fine now, but why are total_used and used_hiwater
> > global variables? If you make them fields in struct io_tlb_mem
> > (possibly guarded with #ifdef CONFIG_DEBUG_FS), you can get rid of the
> > check. Of course, in instances other than io_tlb_default_mem these
> > fields would not be exported to userspace through debugfs, but if really
> > needed, I can at least find them in a crash dump (or read them through
> > /proc/kcore).
> > 
> 
> Got it.
> 
> Your previously comments mentioned making them fields in struct io_tlb_mem,
> and I missed your point.  :-(   I got focused on fixing the accounting for
> DEBUG_FS so it didn't include the non-default pools, and didn't pick up on the
> idea of doing the accounting for the non-default pools even though the values
> aren't exposed in /sys.   I'll fix this in the next version.

FYI, I agree that per-instance accounting is probably the better way,
too.