From: Mike Kravetz <mike.kravetz@oracle.com>
To: Reinette Chatre <reinette.chatre@intel.com>,
tglx@linutronix.de, fenghua.yu@intel.com, tony.luck@intel.com
Cc: gavin.hindman@intel.com, vikas.shivappa@linux.intel.com,
dave.hansen@intel.com, mingo@redhat.com, hpa@zytor.com,
x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Andrew Morton <akpm@linux-foundation.org>,
Michal Hocko <mhocko@suse.com>, Vlastimil Babka <vbabka@suse.cz>
Subject: Re: [RFC PATCH V2 00/22] Intel(R) Resource Director Technology Cache Pseudo-Locking enabling
Date: Thu, 15 Feb 2018 13:10:02 -0800 [thread overview]
Message-ID: <66661860-cb12-1f03-9e89-267d285c52c2@oracle.com> (raw)
In-Reply-To: <c8dbff0b-4d8c-85d9-3f83-539183a95bfa@intel.com>
On 02/15/2018 12:39 PM, Reinette Chatre wrote:
> On 2/14/2018 10:31 AM, Reinette Chatre wrote:
>> On 2/14/2018 10:12 AM, Mike Kravetz wrote:
>>> On 02/13/2018 07:46 AM, Reinette Chatre wrote:
>>>> Adding MM maintainers to v2 to share the new MM change (patch 21/22) that
>>>> enables large contiguous regions that was created to support large Cache
>>>> Pseudo-Locked regions (patch 22/22). This week MM team received another
>>>> proposal to support large contiguous allocations ("[RFC PATCH 0/3]
>>>> Interface for higher order contiguous allocations" at
>>>> http://lkml.kernel.org/r/20180212222056.9735-1-mike.kravetz@oracle.com).
>>>> I have not yet tested with this new proposal but it does seem appropriate
>>>> and I should be able to rework patch 22 from this series on top of that if
>>>> it is accepted instead of what I have in patch 21 of this series.
>>>>
>>>
>>> Well, I certainly would prefer the adoption and use of a more general
>>> purpose interface rather than exposing alloc_gigantic_page().
>>>
>>> Both the interface I suggested and alloc_gigantic_page end up calling
>>> alloc_contig_range(). I have not looked at your entire patch series, but
>>> do be aware that in its present form alloc_contig_range will run into
>>> issues if called by two threads simultaneously for the same page range.
>>> Calling alloc_gigantic_page without some form of synchronization will
>>> expose this issue. Currently this is handled by hugetlb_lock for all
>>> users of alloc_gigantic_page. If you simply expose alloc_gigantic_page
>>> without any type of synchronization, you may run into issues. The first
>>> patch in my RFC "mm: make start_isolate_page_range() fail if already
>>> isolated" should handle this situation IF we decide to expose
>>> alloc_gigantic_page (which I do not suggest).
>>
>> My work depends on the ability to create large contiguous regions,
>> creating these large regions is not the goal in itself. Certainly I
>> would want to use the most appropriate mechanism and I would gladly
>> modify my work to do so.
>>
>> I do not insist on using alloc_gigantic_page(). Now that I am aware of
>> your RFC I started the process to convert to the new
>> find_alloc_contig_pages(). I did not do so earlier because it was not
>> available when I prepared this work for submission. I plan to respond to
>> your RFC when my testing is complete but please give me a few days to do
>> so. Could you please also cc me if you do send out any new versions?
>
> Testing with the new find_alloc_contig_pages() introduced in
> "[RFC PATCH 0/3] Interface for higher order contiguous allocations" at
> http://lkml.kernel.org/r/20180212222056.9735-1-mike.kravetz@oracle.com
> was successful. If this new interface is merged then Cache
> Pseudo-Locking can easily be ported to use that instead of what I have
> in patch 21/22 (exposing alloc_gigantic_page()) with the following
> change to patch 22/22:
>
Nice. Thank you for converting and testing with this interface.
--
Mike Kravetz
>
> diff --git a/arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c
> b/arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c
> index 99918943a98a..b5e4ae379352 100644
> --- a/arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c
> +++ b/arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c
> @@ -228,9 +228,10 @@ static int contig_mem_alloc(struct
> pseudo_lock_region *plr)
> }
>
> if (plr->size > KMALLOC_MAX_SIZE) {
> - plr->kmem = alloc_gigantic_page(cpu_to_node(plr->cpu),
> - get_order(plr->size),
> - GFP_KERNEL | __GFP_ZERO);
> + plr->kmem = find_alloc_contig_pages(get_order(plr->size),
> + GFP_KERNEL | __GFP_ZERO,
> + cpu_to_node(plr->cpu),
> + NULL);
> if (!plr->kmem) {
> rdt_last_cmd_puts("unable to allocate gigantic
> page\n");
> return -ENOMEM;
> @@ -255,7 +256,7 @@ static int contig_mem_alloc(struct
> pseudo_lock_region *plr)
> static void contig_mem_free(struct pseudo_lock_region *plr)
> {
> if (plr->size > KMALLOC_MAX_SIZE)
> - free_gigantic_page(plr->kmem, get_order(plr->size));
> + free_contig_pages(plr->kmem, 1 << get_order(plr->size));
> else
> kfree(page_to_virt(plr->kmem));
> }
>
>
> It does seem as though there will be a new API for large contiguous
> allocations, eliminating the need for patch 21 of this series. How large
> contiguous regions are allocated are independent of Cache Pseudo-Locking
> though and the patch series as submitted still stands. I can include the
> above snippet in a new version of the series but I am not sure if it is
> preferred at this time. Please do let me know, I'd be happy to.
>
> Reinette
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org. For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
>
prev parent reply other threads:[~2018-02-15 21:10 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-13 15:46 [RFC PATCH V2 00/22] Intel(R) Resource Director Technology Cache Pseudo-Locking enabling Reinette Chatre
2018-02-13 15:46 ` [RFC PATCH V2 01/22] x86/intel_rdt: Documentation for Cache Pseudo-Locking Reinette Chatre
2018-02-19 20:35 ` Thomas Gleixner
2018-02-19 22:15 ` Reinette Chatre
2018-02-19 22:19 ` Thomas Gleixner
2018-02-19 22:24 ` Reinette Chatre
2018-02-19 21:27 ` Randy Dunlap
2018-02-19 22:21 ` Reinette Chatre
2018-02-13 15:46 ` [RFC PATCH V2 02/22] x86/intel_rdt: Make useful functions available internally Reinette Chatre
2018-02-13 15:46 ` [RFC PATCH V2 03/22] x86/intel_rdt: Introduce hooks to create pseudo-locking files Reinette Chatre
2018-02-13 15:46 ` [RFC PATCH V2 04/22] x86/intel_rdt: Introduce test to determine if closid is in use Reinette Chatre
2018-02-13 15:46 ` [RFC PATCH V2 05/22] x86/intel_rdt: Print more accurate pseudo-locking availability Reinette Chatre
2018-02-13 15:46 ` [RFC PATCH V2 06/22] x86/intel_rdt: Create pseudo-locked regions Reinette Chatre
2018-02-19 20:57 ` Thomas Gleixner
2018-02-19 23:02 ` Reinette Chatre
2018-02-19 23:16 ` Thomas Gleixner
2018-02-20 3:21 ` Reinette Chatre
2018-02-13 15:46 ` [RFC PATCH V2 07/22] x86/intel_rdt: Connect pseudo-locking directory to operations Reinette Chatre
2018-02-13 15:46 ` [RFC PATCH V2 08/22] x86/intel_rdt: Introduce pseudo-locking resctrl files Reinette Chatre
2018-02-19 21:01 ` Thomas Gleixner
2018-02-13 15:46 ` [RFC PATCH V2 09/22] x86/intel_rdt: Discover supported platforms via prefetch disable bits Reinette Chatre
2018-02-13 15:46 ` [RFC PATCH V2 10/22] x86/intel_rdt: Disable pseudo-locking if CDP enabled Reinette Chatre
2018-02-13 15:46 ` [RFC PATCH V2 11/22] x86/intel_rdt: Associate pseudo-locked regions with its domain Reinette Chatre
2018-02-19 21:19 ` Thomas Gleixner
2018-02-19 23:00 ` Reinette Chatre
2018-02-19 23:19 ` Thomas Gleixner
2018-02-20 3:17 ` Reinette Chatre
2018-02-20 10:00 ` Thomas Gleixner
2018-02-20 16:02 ` Reinette Chatre
2018-02-20 17:18 ` Thomas Gleixner
2018-02-13 15:46 ` [RFC PATCH V2 12/22] x86/intel_rdt: Support CBM checking from value and character buffer Reinette Chatre
2018-02-13 15:46 ` [RFC PATCH V2 13/22] x86/intel_rdt: Support schemata write - pseudo-locking core Reinette Chatre
2018-02-20 17:15 ` Thomas Gleixner
2018-02-20 18:47 ` Reinette Chatre
2018-02-20 23:21 ` Thomas Gleixner
2018-02-21 1:58 ` Mike Kravetz
2018-02-21 6:10 ` Reinette Chatre
2018-02-21 8:34 ` Thomas Gleixner
2018-02-21 5:58 ` Reinette Chatre
2018-02-27 0:34 ` Reinette Chatre
2018-02-27 10:36 ` Thomas Gleixner
2018-02-27 15:38 ` Thomas Gleixner
2018-02-27 19:52 ` Reinette Chatre
2018-02-27 21:33 ` Reinette Chatre
2018-02-28 18:39 ` Thomas Gleixner
2018-02-28 19:17 ` Reinette Chatre
2018-02-28 19:40 ` Thomas Gleixner
2018-02-27 21:01 ` Reinette Chatre
2018-02-28 17:57 ` Thomas Gleixner
2018-02-28 17:59 ` Thomas Gleixner
2018-02-28 18:34 ` Reinette Chatre
2018-02-28 18:42 ` Thomas Gleixner
2018-02-13 15:46 ` [RFC PATCH V2 14/22] x86/intel_rdt: Enable testing for pseudo-locked region Reinette Chatre
2018-02-13 15:46 ` [RFC PATCH V2 15/22] x86/intel_rdt: Prevent new allocations from pseudo-locked regions Reinette Chatre
2018-02-13 15:47 ` [RFC PATCH V2 16/22] x86/intel_rdt: Create debugfs files for pseudo-locking testing Reinette Chatre
2018-02-13 15:47 ` [RFC PATCH V2 17/22] x86/intel_rdt: Create character device exposing pseudo-locked region Reinette Chatre
2018-02-13 15:47 ` [RFC PATCH V2 18/22] x86/intel_rdt: More precise L2 hit/miss measurements Reinette Chatre
2018-02-13 15:47 ` [RFC PATCH V2 19/22] x86/intel_rdt: Support L3 cache performance event of Broadwell Reinette Chatre
2018-02-13 15:47 ` [RFC PATCH V2 20/22] x86/intel_rdt: Limit C-states dynamically when pseudo-locking active Reinette Chatre
2018-02-13 15:47 ` [RFC PATCH V2 21/22] mm/hugetlb: Enable large allocations through gigantic page API Reinette Chatre
2018-02-13 15:47 ` [RFC PATCH V2 22/22] x86/intel_rdt: Support contiguous memory of all sizes Reinette Chatre
2018-02-14 18:12 ` [RFC PATCH V2 00/22] Intel(R) Resource Director Technology Cache Pseudo-Locking enabling Mike Kravetz
2018-02-14 18:31 ` Reinette Chatre
2018-02-15 20:39 ` Reinette Chatre
2018-02-15 21:10 ` Mike Kravetz [this message]
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