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From: Mike Kravetz <mike.kravetz@oracle.com>
To: Mina Almasry <almasrymina@google.com>
Cc: shuah@kernel.org, rientjes@google.com, shakeelb@google.com,
	gthelen@google.com, akpm@linux-foundation.org,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	linux-kselftest@vger.kernel.org, cgroups@vger.kernel.org,
	aneesh.kumar@linux.vnet.ibm.com, mkoutny@suse.com
Subject: Re: [PATCH v9 4/8] hugetlb: disable region_add file_region coalescing
Date: Tue, 21 Jan 2020 09:40:56 -0800
Message-ID: <7fb223ea-3e99-550b-d19c-1352de0d296d@oracle.com> (raw)
In-Reply-To: <2afb05c1-8d85-a0cf-aad1-041054aad529@oracle.com>

On 1/21/20 9:38 AM, Mike Kravetz wrote:
> On 12/17/19 3:16 PM, Mina Almasry wrote:
>> A follow up patch in this series adds hugetlb cgroup uncharge info the
> 
> *nit*
> A follow up patch in this series adds hugetlb cgroup uncharge info to the
> 
>> file_region entries in resv->regions. The cgroup uncharge info may
>> differ for different regions, so they can no longer be coalesced at
>> region_add time. So, disable region coalescing in region_add in this
>> patch.
>>
>> Behavior change:
>>
>> Say a resv_map exists like this [0->1], [2->3], and [5->6].
>>
>> Then a region_chg/add call comes in region_chg/add(f=0, t=5).
>>
>> Old code would generate resv->regions: [0->5], [5->6].
>> New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5],
>> [5->6].
>>
>> Special care needs to be taken to handle the resv->adds_in_progress
>> variable correctly. In the past, only 1 region would be added for every
>> region_chg and region_add call. But now, each call may add multiple
>> regions, so we can no longer increment adds_in_progress by 1 in region_chg,
>> or decrement adds_in_progress by 1 after region_add or region_abort. Instead,
>> region_chg calls add_reservation_in_range() to count the number of regions
>> needed and allocates those, and that info is passed to region_add and
>> region_abort to decrement adds_in_progress correctly.
>>
>> We've also modified the assumption that region_add after region_chg
>> never fails. region_chg now pre-allocates at least 1 region for
>> region_add. If region_add needs more regions than region_chg has
>> allocated for it, then it may fail.
>>
>> Signed-off-by: Mina Almasry <almasrymina@google.com>
>> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
> 
> Thanks for the updated comments.  Still,
> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>


Sorry, that comment was directed at V10 of the patch.

-- 
Mike Kravetz

  reply index

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-17 23:16 [PATCH v9 1/8] hugetlb_cgroup: Add hugetlb_cgroup reservation counter Mina Almasry
2019-12-17 23:16 ` [PATCH v9 2/8] hugetlb_cgroup: add interface for charge/uncharge hugetlb reservations Mina Almasry
2020-01-13 22:14   ` Mike Kravetz
2020-01-14  0:45     ` David Rientjes
2020-01-14 22:55     ` Mina Almasry
2019-12-17 23:16 ` [PATCH v9 3/8] hugetlb_cgroup: add reservation accounting for private mappings Mina Almasry
2020-01-14  0:55   ` Mike Kravetz
2020-01-14 22:52     ` Mina Almasry
2020-01-17 22:09       ` Mike Kravetz
2020-01-22 21:40         ` Mina Almasry
2019-12-17 23:16 ` [PATCH v9 4/8] hugetlb: disable region_add file_region coalescing Mina Almasry
2020-01-21 17:38   ` Mike Kravetz
2020-01-21 17:40     ` Mike Kravetz [this message]
2019-12-17 23:16 ` [PATCH v9 5/8] hugetlb_cgroup: add accounting for shared mappings Mina Almasry
2019-12-17 23:16 ` [PATCH v9 6/8] hugetlb_cgroup: support noreserve mappings Mina Almasry
2020-01-14  0:48   ` David Rientjes
2019-12-17 23:16 ` [PATCH v9 7/8] hugetlb_cgroup: Add hugetlb_cgroup reservation tests Mina Almasry
2019-12-17 23:16 ` [PATCH v9 8/8] hugetlb_cgroup: Add hugetlb_cgroup reservation docs Mina Almasry
2020-01-14  0:54   ` David Rientjes
2019-12-19  1:12 ` [PATCH v9 1/8] hugetlb_cgroup: Add hugetlb_cgroup reservation counter Andrew Morton
2019-12-19  1:37   ` Mike Kravetz
2019-12-19  1:59     ` Mina Almasry
2020-01-13 18:43 ` Mike Kravetz
2020-01-13 21:03   ` Mina Almasry
2020-01-13 22:05     ` Mike Kravetz
2020-01-13 22:21       ` Mina Almasry
2020-01-14  0:45 ` David Rientjes

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