From: Andrew Morton <akpm@linux-foundation.org> To: Rik van Riel <riel@redhat.com> Cc: linux-mm@kvack.org, aarcange@redhat.com, peterz@infradead.org, minchan@gmail.com, kosaki.motohiro@gmail.com, andi@firstfloor.org, hannes@cmpxchg.org, mel@csn.ul.ie, linux-kernel@vger.kernel.org, Rik van Riel <riel@surriel.com> Subject: Re: [PATCH -mm 1/7] mm: track free size between VMAs in VMA rbtree Date: Tue, 19 Jun 2012 16:25:47 -0700 [thread overview] Message-ID: <20120619162547.d35e759e.akpm@linux-foundation.org> (raw) In-Reply-To: <1340057126-31143-2-git-send-email-riel@redhat.com> On Mon, 18 Jun 2012 18:05:20 -0400 Rik van Riel <riel@redhat.com> wrote: > From: Rik van Riel <riel@surriel.com> > > Track the size of free areas between VMAs in the VMA rbtree. > > This will allow get_unmapped_area_* to find a free area of the > right size in O(log(N)) time, instead of potentially having to > do a linear walk across all the VMAs. > > ... > > --- a/include/linux/mm_types.h > +++ b/include/linux/mm_types.h > @@ -213,6 +213,13 @@ struct vm_area_struct { > struct rb_node vm_rb; > > /* > + * Largest free memory gap "behind" this VMA (in the direction mmap > + * grows from), or of VMAs down the rb tree below us. This helps > + * get_unmapped_area find a free area of the right size. > + */ > + unsigned long free_gap; Please mention the units? Seems to be "bytes", not "pages". > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -205,6 +205,51 @@ static void __remove_shared_vm_struct(struct vm_area_struct *vma, > flush_dcache_mmap_unlock(mapping); > } > > +static unsigned long max_free_space(struct rb_node *node) > +{ > + struct vm_area_struct *vma, *prev, *left = NULL, *right = NULL; > + unsigned long largest = 0; > + > + if (node->rb_left) > + left = rb_to_vma(node->rb_left); > + if (node->rb_right) > + right = rb_to_vma(node->rb_right); > + > + /* > + * Calculate the free gap size between us and the > + * VMA to our left. > + */ Comment will fit in a single line. > + vma = rb_to_vma(node); > + prev = vma->vm_prev; > + > + if (prev) > + largest = vma->vm_start - prev->vm_end; > + else > + largest = vma->vm_start; > + > + /* We propagate the largest of our own, or our children's free gaps. */ > + if (left) > + largest = max(largest, left->free_gap); > + if (right) > + largest = max(largest, right->free_gap); > + > + return largest; > +} This would be easier to review if it had a nice comment explaining its role ;) > +static void vma_rb_augment_cb(struct rb_node *node, void *__unused) > +{ > + struct vm_area_struct *vma; > + > + vma = rb_to_vma(node); > + > + vma->free_gap = max_free_space(node); > +} Save some trees! struct vm_area_struct *vma = rb_to_vma(node); vma->free_gap = max_free_space(node); or even rb_to_vma(node)->free_gap = max_free_space(node); Major stuff, huh?
WARNING: multiple messages have this Message-ID (diff)
From: Andrew Morton <akpm@linux-foundation.org> To: Rik van Riel <riel@redhat.com> Cc: linux-mm@kvack.org, aarcange@redhat.com, peterz@infradead.org, minchan@gmail.com, kosaki.motohiro@gmail.com, andi@firstfloor.org, hannes@cmpxchg.org, mel@csn.ul.ie, linux-kernel@vger.kernel.org, Rik van Riel <riel@surriel.com> Subject: Re: [PATCH -mm 1/7] mm: track free size between VMAs in VMA rbtree Date: Tue, 19 Jun 2012 16:25:47 -0700 [thread overview] Message-ID: <20120619162547.d35e759e.akpm@linux-foundation.org> (raw) In-Reply-To: <1340057126-31143-2-git-send-email-riel@redhat.com> On Mon, 18 Jun 2012 18:05:20 -0400 Rik van Riel <riel@redhat.com> wrote: > From: Rik van Riel <riel@surriel.com> > > Track the size of free areas between VMAs in the VMA rbtree. > > This will allow get_unmapped_area_* to find a free area of the > right size in O(log(N)) time, instead of potentially having to > do a linear walk across all the VMAs. > > ... > > --- a/include/linux/mm_types.h > +++ b/include/linux/mm_types.h > @@ -213,6 +213,13 @@ struct vm_area_struct { > struct rb_node vm_rb; > > /* > + * Largest free memory gap "behind" this VMA (in the direction mmap > + * grows from), or of VMAs down the rb tree below us. This helps > + * get_unmapped_area find a free area of the right size. > + */ > + unsigned long free_gap; Please mention the units? Seems to be "bytes", not "pages". > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -205,6 +205,51 @@ static void __remove_shared_vm_struct(struct vm_area_struct *vma, > flush_dcache_mmap_unlock(mapping); > } > > +static unsigned long max_free_space(struct rb_node *node) > +{ > + struct vm_area_struct *vma, *prev, *left = NULL, *right = NULL; > + unsigned long largest = 0; > + > + if (node->rb_left) > + left = rb_to_vma(node->rb_left); > + if (node->rb_right) > + right = rb_to_vma(node->rb_right); > + > + /* > + * Calculate the free gap size between us and the > + * VMA to our left. > + */ Comment will fit in a single line. > + vma = rb_to_vma(node); > + prev = vma->vm_prev; > + > + if (prev) > + largest = vma->vm_start - prev->vm_end; > + else > + largest = vma->vm_start; > + > + /* We propagate the largest of our own, or our children's free gaps. */ > + if (left) > + largest = max(largest, left->free_gap); > + if (right) > + largest = max(largest, right->free_gap); > + > + return largest; > +} This would be easier to review if it had a nice comment explaining its role ;) > +static void vma_rb_augment_cb(struct rb_node *node, void *__unused) > +{ > + struct vm_area_struct *vma; > + > + vma = rb_to_vma(node); > + > + vma->free_gap = max_free_space(node); > +} Save some trees! struct vm_area_struct *vma = rb_to_vma(node); vma->free_gap = max_free_space(node); or even rb_to_vma(node)->free_gap = max_free_space(node); Major stuff, huh? -- 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>
next prev parent reply other threads:[~2012-06-19 23:25 UTC|newest] Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-06-18 22:05 [PATCH -mm 0/7] mm: scalable and unified arch_get_unmapped_area Rik van Riel 2012-06-18 22:05 ` Rik van Riel 2012-06-18 22:05 ` [PATCH -mm 1/7] mm: track free size between VMAs in VMA rbtree Rik van Riel 2012-06-18 22:05 ` Rik van Riel 2012-06-19 23:25 ` Andrew Morton [this message] 2012-06-19 23:25 ` Andrew Morton 2012-06-21 11:01 ` Peter Zijlstra 2012-06-21 11:01 ` Peter Zijlstra 2012-06-21 11:07 ` Peter Zijlstra 2012-06-21 11:07 ` Peter Zijlstra 2012-06-21 14:47 ` Mel Gorman 2012-06-21 14:47 ` Mel Gorman 2012-06-18 22:05 ` [PATCH -mm 2/7] mm: get unmapped area from VMA tree Rik van Riel 2012-06-18 22:05 ` Rik van Riel 2012-06-21 9:01 ` Johannes Weiner 2012-06-21 9:01 ` Johannes Weiner 2012-06-21 13:17 ` Rik van Riel 2012-06-21 13:17 ` Rik van Riel 2012-06-21 16:50 ` Rik van Riel 2012-06-21 16:50 ` Rik van Riel 2012-06-21 16:16 ` Mel Gorman 2012-06-21 16:16 ` Mel Gorman 2012-06-21 17:27 ` Rik van Riel 2012-06-21 17:27 ` Rik van Riel 2012-06-21 21:06 ` Peter Zijlstra 2012-06-21 21:06 ` Peter Zijlstra 2012-06-18 22:05 ` [PATCH -mm 3/7] Allow each architecture to specify the address range that can be used for this allocation Rik van Riel 2012-06-18 22:05 ` Rik van Riel 2012-06-18 22:05 ` [PATCH -mm 4/7] mm: make page colouring code generic Rik van Riel 2012-06-18 22:05 ` Rik van Riel 2012-06-19 23:27 ` Andrew Morton 2012-06-19 23:27 ` Andrew Morton 2012-06-21 17:52 ` Rik van Riel 2012-06-21 17:52 ` Rik van Riel 2012-06-21 19:22 ` Borislav Petkov 2012-06-21 19:22 ` Borislav Petkov 2012-06-21 11:20 ` Peter Zijlstra 2012-06-21 11:20 ` Peter Zijlstra 2012-06-21 14:30 ` Rik van Riel 2012-06-21 14:30 ` Rik van Riel 2012-06-21 17:40 ` Andrew Morton 2012-06-21 17:40 ` Andrew Morton 2012-06-21 17:45 ` Rik van Riel 2012-06-21 17:45 ` Rik van Riel 2012-06-21 12:37 ` Borislav Petkov 2012-06-21 12:37 ` Borislav Petkov 2012-06-21 13:24 ` Rik van Riel 2012-06-21 13:24 ` Rik van Riel 2012-06-18 22:05 ` [PATCH -mm 5/7] mm: remove x86 arch_get_unmapped_area(_topdown) Rik van Riel 2012-06-18 22:05 ` Rik van Riel 2012-06-18 22:05 ` [PATCH -mm 6/7] remove MIPS arch_get_unmapped_area code Rik van Riel 2012-06-18 22:05 ` Rik van Riel 2012-06-18 22:05 ` [PATCH -mm 7/7] remove ARM arch_get_unmapped_area functions Rik van Riel 2012-06-18 22:05 ` Rik van Riel 2012-06-19 23:20 ` [PATCH -mm 0/7] mm: scalable and unified arch_get_unmapped_area Andrew Morton 2012-06-19 23:20 ` Andrew Morton 2012-06-21 10:18 ` Johannes Weiner 2012-06-21 10:18 ` Johannes Weiner
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