From: Alexander Duyck <alexander.h.duyck@linux.intel.com>
To: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux-nvdimm@lists.01.org
Cc: pavel.tatashin@microsoft.com, mhocko@suse.com,
dave.hansen@intel.com, jglisse@redhat.com,
akpm@linux-foundation.org, mingo@kernel.org,
kirill.shutemov@linux.intel.com
Subject: [PATCH v4 2/5] mm: Create non-atomic version of SetPageReserved for init use
Date: Thu, 20 Sep 2018 15:27:53 -0700 [thread overview]
Message-ID: <20180920222641.19464.75787.stgit@localhost.localdomain> (raw)
In-Reply-To: <20180920215824.19464.8884.stgit@localhost.localdomain>
It doesn't make much sense to use the atomic SetPageReserved at init time
when we are using memset to clear the memory and manipulating the page
flags via simple "&=" and "|=" operations in __init_single_page.
This patch adds a non-atomic version __SetPageReserved that can be used
during page init and shows about a 10% improvement in initialization times
on the systems I have available for testing. On those systems I saw
initialization times drop from around 35 seconds to around 32 seconds to
initialize a 3TB block of persistent memory. I believe the main advantage
of this is that it allows for more compiler optimization as the __set_bit
operation can be reordered whereas the atomic version cannot.
I tried adding a bit of documentation based on commit <f1dd2cd13c4> ("mm,
memory_hotplug: do not associate hotadded memory to zones until online").
Ideally the reserved flag should be set earlier since there is a brief
window where the page is initialization via __init_single_page and we have
not set the PG_Reserved flag. I'm leaving that for a future patch set as
that will require a more significant refactor.
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
---
v4: Added comment about __set_bit vs set_bit to the patch description
include/linux/page-flags.h | 1 +
mm/page_alloc.c | 9 +++++++--
2 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 934f91ef3f54..50ce1bddaf56 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -303,6 +303,7 @@ static inline void page_init_poison(struct page *page, size_t size)
PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
__CLEARPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
+ __SETPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
PAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
__CLEARPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
__SETPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 712cab17f86f..29bd662fffd7 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1239,7 +1239,12 @@ void __meminit reserve_bootmem_region(phys_addr_t start, phys_addr_t end)
/* Avoid false-positive PageTail() */
INIT_LIST_HEAD(&page->lru);
- SetPageReserved(page);
+ /*
+ * no need for atomic set_bit because the struct
+ * page is not visible yet so nobody should
+ * access it yet.
+ */
+ __SetPageReserved(page);
}
}
}
@@ -5513,7 +5518,7 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
page = pfn_to_page(pfn);
__init_single_page(page, pfn, zone, nid);
if (context == MEMMAP_HOTPLUG)
- SetPageReserved(page);
+ __SetPageReserved(page);
/*
* Mark the block movable so that blocks are reserved for
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next prev parent reply other threads:[~2018-09-20 22:27 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-20 22:24 [PATCH v4 0/5] Address issues slowing persistent memory initialization Alexander Duyck
2018-09-20 22:26 ` [PATCH v4 1/5] mm: Provide kernel parameter to allow disabling page init poisoning Alexander Duyck
2018-09-21 19:04 ` Pasha Tatashin
2018-09-21 19:41 ` Logan Gunthorpe
2018-09-21 19:52 ` Pasha Tatashin
2018-09-20 22:27 ` Alexander Duyck [this message]
2018-09-21 19:06 ` [PATCH v4 2/5] mm: Create non-atomic version of SetPageReserved for init use Pasha Tatashin
2018-09-20 22:29 ` [PATCH v4 3/5] mm: Defer ZONE_DEVICE page initialization to the point where we init pgmap Alexander Duyck
2018-09-21 19:50 ` Pasha Tatashin
2018-09-21 20:03 ` Alexander Duyck
2018-09-21 20:14 ` Pasha Tatashin
2018-09-20 22:29 ` [PATCH v4 4/5] async: Add support for queueing on specific node Alexander Duyck
2018-09-21 14:57 ` Dan Williams
2018-09-21 17:02 ` Alexander Duyck
2018-09-29 8:15 ` [LKP] [async] 06f4f5bfb3: BUG:sleeping_function_called_from_invalid_context_at_include/linux/percpu-rwsem.h kernel test robot
2018-09-20 22:29 ` [PATCH v4 5/5] nvdimm: Schedule device registration on node local to the device Alexander Duyck
2018-09-20 22:59 ` Dan Williams
2018-09-21 0:16 ` Alexander Duyck
2018-09-21 0:36 ` Dan Williams
2018-09-21 1:33 ` Alexander Duyck
2018-09-21 2:46 ` Dan Williams
2018-09-21 14:46 ` Alexander Duyck
2018-09-21 14:56 ` Dan Williams
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