From: David Hildenbrand <david@redhat.com>
To: Pasha Tatashin <pasha.tatashin@soleen.com>,
akpm@linux-foundation.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, rientjes@google.com,
dwmw2@infradead.org, baolu.lu@linux.intel.com, joro@8bytes.org,
will@kernel.org, robin.murphy@arm.com, iommu@lists.linux.dev,
Matthew Wilcox <willy@infradead.org>
Subject: Re: [RFC v2 0/3] iommu/intel: Free empty page tables on unmaps
Date: Fri, 26 Apr 2024 08:42:34 +0200 [thread overview]
Message-ID: <2daf168e-e2b2-4b19-9b39-d58b358c8cd9@redhat.com> (raw)
In-Reply-To: <20240426034323.417219-1-pasha.tatashin@soleen.com>
On 26.04.24 05:43, Pasha Tatashin wrote:
> Changelog
> ================================================================
> v2: Use mapcount instead of refcount
> Synchronized with IOMMU Observability changes.
> ================================================================
>
> This series frees empty page tables on unmaps. It intends to be a
> low overhead feature.
>
> The read-writer lock is used to synchronize page table, but most of
> time the lock is held is reader. It is held as a writer for short
> period of time when unmapping a page that is bigger than the current
> iova request. For all other cases this lock is read-only.
>
> page->mapcount is used in order to track number of entries at each page
> table.
I'm wondering if this will conflict with page_type at some point? We're
already converting other page table users to ptdesc. CCing Willy.
--
Cheers,
David / dhildenb
next prev parent reply other threads:[~2024-04-26 6:42 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-26 3:43 [RFC v2 0/3] iommu/intel: Free empty page tables on unmaps Pasha Tatashin
2024-04-26 3:43 ` [RFC v2 1/3] iommu/intel: Use page->_mapcount to count number of entries in IOMMU Pasha Tatashin
2024-04-26 3:43 ` [RFC v2 2/3] iommu/intel: synchronize page table map and unmap operations Pasha Tatashin
2024-04-29 14:56 ` Jason Gunthorpe
2024-04-26 3:43 ` [RFC v2 3/3] iommu/intel: free empty page tables on unmaps Pasha Tatashin
2024-04-26 6:42 ` David Hildenbrand [this message]
2024-04-26 13:49 ` [RFC v2 0/3] iommu/intel: Free " Pasha Tatashin
2024-04-26 14:39 ` David Hildenbrand
2024-04-26 19:39 ` Matthew Wilcox
2024-04-29 14:46 ` Jason Gunthorpe
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