shaba/lvm2
1
0
Fork 0
mirror of git://sourceware.org/git/lvm2.git synced 2025-01-03 05:18:29 +03:00
Code Releases Activity

Optimise PV segments search.

Browse Source 
The function find_peg_by_pe is incredibly inefficient
for Pvs with many segments.

In shiny future there should be binary (or interval) tree
instead of sorted linked list (volunteers?).

Anyway, for now, we can use dirty trick here to optimise this case:

 - Allocations are usually applied from the beginning
 of PV (we have no alloocation policy which allocates areas
 "backwards")

 - The only user of find_peg_by_pe is pv_split_segment()
 call. In *most* cases it need to split *last* PV segment.

So if we search sorted pv segment list backwards, we
hit the requested segment immediatelly.

This patch applies this tiny change.
(and saves >30% of processing time when >3000LVs segments are on one PV!)

To discourage using this inefficient function from other code,
it is moved to pv_manip.c and used static for now:-)
This commit is contained in:
Milan Broz 2010-03-31 17:21:40 +00:00
parent c8b0988586
commit 80b96a8974
4 changed files with 15 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
WHATS_NEW
View File

@ -1,5 +1,6 @@
Version 2.02.63 -
================================
Optimise PV segments search for the most last segment search case.
Remove vg_validate call when parsing cached metadata.
Use hash table of LVs to speed up parsing of text metadata with many LVs.
Fix two messages, add a whitespace and parentheses

12
lib/metadata/metadata.c
View File

@ -1799,18 +1799,6 @@ struct lv_segment *first_seg(const struct logical_volume *lv)
return NULL;
}
/* Find segment at a given physical extent in a PV */
struct pv_segment *find_peg_by_pe(const struct physical_volume *pv, uint32_t pe)
{
struct pv_segment *peg;
dm_list_iterate_items(peg, &pv->segments)
if (pe >= peg->pe && pe < peg->pe + peg->len)
return peg;
return NULL;
}
int vg_remove_mdas(struct volume_group *vg)
{
struct metadata_area *mda;

3
lib/metadata/metadata.h
View File

@ -308,9 +308,6 @@ struct pv_list *find_pv_in_pv_list(const struct dm_list *pl,
/* Find LV segment containing given LE */
struct lv_segment *find_seg_by_le(const struct logical_volume *lv, uint32_t le);
/* Find PV segment containing given LE */
struct pv_segment *find_peg_by_pe(const struct physical_volume *pv, uint32_t pe);
/*
* Remove a dev_dir if present.
*/

14
lib/metadata/pv_manip.c
View File

@ -78,6 +78,20 @@ int peg_dup(struct dm_pool *mem, struct dm_list *peg_new, struct dm_list *peg_ol
return 1;
}
/* Find segment at a given physical extent in a PV */
static struct pv_segment *find_peg_by_pe(const struct physical_volume *pv,
uint32_t pe)
{
struct pv_segment *pvseg;
/* search backwards to optimise mostly used last segment split */
dm_list_iterate_back_items(pvseg, &pv->segments)
if (pe >= pvseg->pe && pe < pvseg->pe + pvseg->len)
return pvseg;
return NULL;
}
/*
* Split peg at given extent.
* Second part is always deallocated.