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https://github.com/torvalds/linux
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f7f82b81d2
Walking backref tree and btrfs quota rely on ulist very much. This patch tries to use rb_tree to speed up search time. The original code always checks whether an element exists before adding a new element, however it costs O(n). I try to add a rb_tree in the ulist,this is only used to speed up search. I also do some measurements with quota enabled. fsstress -p 4 -n 10000 Without this path: real 0m51.058s 2m4.745s 1m28.222s 1m5.137s user 0m0.035s 0m0.041s 0m0.105s 0m0.100s sys 0m12.009s 0m11.246s 0m10.901s 0m10.999s 0m11.287s With this path: real 0m55.295s 0m50.960s 1m2.214s 0m48.273s user 0m0.053s 0m0.095s 0m0.135s 0m0.107s sys 0m7.766s 0m6.013s 0m6.319s 0m6.030s 0m6.532s After applying the patch,the execute time is down by ~42%.(11.287s->6.532s) Signed-off-by: Wang Shilong <wangsl-fnst@cn.fujitsu.com> Reviewed-by: Miao Xie <miaox@cn.fujitsu.com> Reviewed-by: Jan Schmidt <list.btrfs@jan-o-sch.net> Signed-off-by: Josef Bacik <jbacik@fusionio.com>
82 lines
2 KiB
C
82 lines
2 KiB
C
/*
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* Copyright (C) 2011 STRATO AG
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* written by Arne Jansen <sensille@gmx.net>
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* Distributed under the GNU GPL license version 2.
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*
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*/
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#ifndef __ULIST__
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#define __ULIST__
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#include <linux/list.h>
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#include <linux/rbtree.h>
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/*
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* ulist is a generic data structure to hold a collection of unique u64
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* values. The only operations it supports is adding to the list and
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* enumerating it.
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* It is possible to store an auxiliary value along with the key.
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*
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* The implementation is preliminary and can probably be sped up
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* significantly. A first step would be to store the values in an rbtree
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* as soon as ULIST_SIZE is exceeded.
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*/
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/*
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* number of elements statically allocated inside struct ulist
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*/
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#define ULIST_SIZE 16
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struct ulist_iterator {
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int i;
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};
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/*
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* element of the list
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*/
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struct ulist_node {
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u64 val; /* value to store */
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u64 aux; /* auxiliary value saved along with the val */
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struct rb_node rb_node; /* used to speed up search */
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};
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struct ulist {
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/*
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* number of elements stored in list
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*/
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unsigned long nnodes;
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/*
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* number of nodes we already have room for
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*/
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unsigned long nodes_alloced;
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/*
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* pointer to the array storing the elements. The first ULIST_SIZE
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* elements are stored inline. In this case the it points to int_nodes.
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* After exceeding ULIST_SIZE, dynamic memory is allocated.
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*/
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struct ulist_node *nodes;
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struct rb_root root;
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/*
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* inline storage space for the first ULIST_SIZE entries
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*/
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struct ulist_node int_nodes[ULIST_SIZE];
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};
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void ulist_init(struct ulist *ulist);
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void ulist_fini(struct ulist *ulist);
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void ulist_reinit(struct ulist *ulist);
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struct ulist *ulist_alloc(gfp_t gfp_mask);
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void ulist_free(struct ulist *ulist);
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int ulist_add(struct ulist *ulist, u64 val, u64 aux, gfp_t gfp_mask);
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int ulist_add_merge(struct ulist *ulist, u64 val, u64 aux,
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u64 *old_aux, gfp_t gfp_mask);
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struct ulist_node *ulist_next(struct ulist *ulist,
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struct ulist_iterator *uiter);
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#define ULIST_ITER_INIT(uiter) ((uiter)->i = 0)
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#endif
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