/[pkg-src]/trunk/kernel26-alx/patches-2.6.20-r5/0022-2.6.20-mm-filesize_dependant_lru_cache_add.patch |
Annotation of /trunk/kernel26-alx/patches-2.6.20-r5/0022-2.6.20-mm-filesize_dependant_lru_cache_add.patch
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Revision 199 -
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Fri May 18 11:04:36 2007 UTC (17 years, 4 months ago) by niro
File size: 6637 byte(s)
Fri May 18 11:04:36 2007 UTC (17 years, 4 months ago) by niro
File size: 6637 byte(s)
-import
1 | niro | 199 | When reading from large files through the generic file read functions into |
2 | page cache we can detect when a file is so large that it is unlikely to be | ||
3 | fully cached in ram. | ||
4 | |||
5 | Add a tunable /proc/sys/vm/tail_largefiles that puts them at the tail of the | ||
6 | inactive list to minimise their harm on present mapped pages and pagecache | ||
7 | and enable it by default. | ||
8 | |||
9 | Signed-off-by: Con Kolivas <kernel@kolivas.org> | ||
10 | |||
11 | --- | ||
12 | Documentation/filesystems/proc.txt | 8 +++++ | ||
13 | Documentation/sysctl/vm.txt | 2 - | ||
14 | include/linux/sysctl.h | 1 | ||
15 | kernel/sysctl.c | 9 ++++++ | ||
16 | mm/filemap.c | 53 +++++++++++++++++++++++++++++++++++-- | ||
17 | mm/swap.c | 3 -- | ||
18 | 6 files changed, 71 insertions(+), 5 deletions(-) | ||
19 | |||
20 | Index: linux-2.6.20-ck1/mm/filemap.c | ||
21 | =================================================================== | ||
22 | --- linux-2.6.20-ck1.orig/mm/filemap.c 2007-02-05 22:52:04.000000000 +1100 | ||
23 | +++ linux-2.6.20-ck1/mm/filemap.c 2007-02-16 19:01:34.000000000 +1100 | ||
24 | @@ -466,6 +466,16 @@ int add_to_page_cache_lru(struct page *p | ||
25 | return ret; | ||
26 | } | ||
27 | |||
28 | +int add_to_page_cache_lru_tail(struct page *page, | ||
29 | + struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask) | ||
30 | +{ | ||
31 | + int ret = add_to_page_cache(page, mapping, offset, gfp_mask); | ||
32 | + | ||
33 | + if (ret == 0) | ||
34 | + lru_cache_add_tail(page); | ||
35 | + return ret; | ||
36 | +} | ||
37 | + | ||
38 | #ifdef CONFIG_NUMA | ||
39 | struct page *__page_cache_alloc(gfp_t gfp) | ||
40 | { | ||
41 | @@ -856,6 +866,34 @@ static void shrink_readahead_size_eio(st | ||
42 | ra->ra_pages /= 4; | ||
43 | } | ||
44 | |||
45 | +/* | ||
46 | + * Sysctl which determines whether we should read from large files to the | ||
47 | + * tail of the inactive lru list. | ||
48 | + */ | ||
49 | +int vm_tail_largefiles __read_mostly = 1; | ||
50 | + | ||
51 | +static inline int nr_mapped(void) | ||
52 | +{ | ||
53 | + return global_page_state(NR_FILE_MAPPED) + | ||
54 | + global_page_state(NR_ANON_PAGES); | ||
55 | +} | ||
56 | + | ||
57 | +/* | ||
58 | + * This examines how large in pages a file size is and returns 1 if it is | ||
59 | + * more than half the unmapped ram. Avoid doing read_page_state which is | ||
60 | + * expensive unless we already know it is likely to be large enough. | ||
61 | + */ | ||
62 | +static int large_isize(unsigned long nr_pages) | ||
63 | +{ | ||
64 | + if (nr_pages * 6 > vm_total_pages) { | ||
65 | + unsigned long unmapped_ram = vm_total_pages - nr_mapped(); | ||
66 | + | ||
67 | + if (nr_pages * 2 > unmapped_ram) | ||
68 | + return 1; | ||
69 | + } | ||
70 | + return 0; | ||
71 | +} | ||
72 | + | ||
73 | /** | ||
74 | * do_generic_mapping_read - generic file read routine | ||
75 | * @mapping: address_space to be read | ||
76 | @@ -1064,8 +1102,19 @@ no_cached_page: | ||
77 | goto out; | ||
78 | } | ||
79 | } | ||
80 | - error = add_to_page_cache_lru(cached_page, mapping, | ||
81 | - index, GFP_KERNEL); | ||
82 | + | ||
83 | + /* | ||
84 | + * If we know the file is large we add the pages read to the | ||
85 | + * end of the lru as we're unlikely to be able to cache the | ||
86 | + * whole file in ram so make those pages the first to be | ||
87 | + * dropped if not referenced soon. | ||
88 | + */ | ||
89 | + if (vm_tail_largefiles && large_isize(end_index)) | ||
90 | + error = add_to_page_cache_lru_tail(cached_page, | ||
91 | + mapping, index, GFP_KERNEL); | ||
92 | + else | ||
93 | + error = add_to_page_cache_lru(cached_page, mapping, | ||
94 | + index, GFP_KERNEL); | ||
95 | if (error) { | ||
96 | if (error == -EEXIST) | ||
97 | goto find_page; | ||
98 | Index: linux-2.6.20-ck1/mm/swap.c | ||
99 | =================================================================== | ||
100 | --- linux-2.6.20-ck1.orig/mm/swap.c 2007-02-16 19:01:33.000000000 +1100 | ||
101 | +++ linux-2.6.20-ck1/mm/swap.c 2007-02-16 19:01:34.000000000 +1100 | ||
102 | @@ -434,8 +434,7 @@ void __pagevec_lru_add_active(struct pag | ||
103 | |||
104 | /* | ||
105 | * Function used uniquely to put pages back to the lru at the end of the | ||
106 | - * inactive list to preserve the lru order. Currently only used by swap | ||
107 | - * prefetch. | ||
108 | + * inactive list to preserve the lru order. | ||
109 | */ | ||
110 | void fastcall lru_cache_add_tail(struct page *page) | ||
111 | { | ||
112 | Index: linux-2.6.20-ck1/kernel/sysctl.c | ||
113 | =================================================================== | ||
114 | --- linux-2.6.20-ck1.orig/kernel/sysctl.c 2007-02-16 19:01:33.000000000 +1100 | ||
115 | +++ linux-2.6.20-ck1/kernel/sysctl.c 2007-02-16 19:01:34.000000000 +1100 | ||
116 | @@ -77,6 +77,7 @@ extern int pid_max_min, pid_max_max; | ||
117 | extern int sysctl_drop_caches; | ||
118 | extern int percpu_pagelist_fraction; | ||
119 | extern int compat_log; | ||
120 | +extern int vm_tail_largefiles; | ||
121 | |||
122 | /* this is needed for the proc_dointvec_minmax for [fs_]overflow UID and GID */ | ||
123 | static int maxolduid = 65535; | ||
124 | @@ -918,6 +919,14 @@ static ctl_table vm_table[] = { | ||
125 | .mode = 0644, | ||
126 | .proc_handler = &proc_dointvec, | ||
127 | }, | ||
128 | + { | ||
129 | + .ctl_name = VM_TAIL_LARGEFILES, | ||
130 | + .procname = "tail_largefiles", | ||
131 | + .data = &vm_tail_largefiles, | ||
132 | + .maxlen = sizeof(int), | ||
133 | + .mode = 0644, | ||
134 | + .proc_handler = &proc_dointvec, | ||
135 | + }, | ||
136 | #ifdef CONFIG_HUGETLB_PAGE | ||
137 | { | ||
138 | .ctl_name = VM_HUGETLB_PAGES, | ||
139 | Index: linux-2.6.20-ck1/Documentation/filesystems/proc.txt | ||
140 | =================================================================== | ||
141 | --- linux-2.6.20-ck1.orig/Documentation/filesystems/proc.txt 2007-02-05 22:51:59.000000000 +1100 | ||
142 | +++ linux-2.6.20-ck1/Documentation/filesystems/proc.txt 2007-02-16 19:01:34.000000000 +1100 | ||
143 | @@ -1324,6 +1324,14 @@ To free pagecache, dentries and inodes: | ||
144 | As this is a non-destructive operation and dirty objects are not freeable, the | ||
145 | user should run `sync' first. | ||
146 | |||
147 | +tail_largefiles | ||
148 | +--------------- | ||
149 | + | ||
150 | +When enabled reads from large files to the tail end of the inactive lru list. | ||
151 | +This means that any cache from reading large files is dropped very quickly, | ||
152 | +preventing loss of mapped ram and useful pagecache when large files are read. | ||
153 | +This does, however, make caching less effective when working with large files. | ||
154 | + | ||
155 | |||
156 | 2.5 /proc/sys/dev - Device specific parameters | ||
157 | ---------------------------------------------- | ||
158 | Index: linux-2.6.20-ck1/Documentation/sysctl/vm.txt | ||
159 | =================================================================== | ||
160 | --- linux-2.6.20-ck1.orig/Documentation/sysctl/vm.txt 2007-02-16 19:01:33.000000000 +1100 | ||
161 | +++ linux-2.6.20-ck1/Documentation/sysctl/vm.txt 2007-02-16 19:01:34.000000000 +1100 | ||
162 | @@ -39,7 +39,7 @@ Currently, these files are in /proc/sys/ | ||
163 | |||
164 | dirty_ratio, dirty_background_ratio, dirty_expire_centisecs, | ||
165 | dirty_writeback_centisecs, vfs_cache_pressure, laptop_mode, | ||
166 | -block_dump, swap_token_timeout, drop-caches: | ||
167 | +block_dump, swap_token_timeout, drop-caches, tail_largefiles: | ||
168 | |||
169 | See Documentation/filesystems/proc.txt | ||
170 | |||
171 | Index: linux-2.6.20-ck1/include/linux/sysctl.h | ||
172 | =================================================================== | ||
173 | --- linux-2.6.20-ck1.orig/include/linux/sysctl.h 2007-02-16 19:01:33.000000000 +1100 | ||
174 | +++ linux-2.6.20-ck1/include/linux/sysctl.h 2007-02-16 19:01:34.000000000 +1100 | ||
175 | @@ -204,6 +204,7 @@ enum | ||
176 | VM_MIN_SLAB=35, /* Percent pages ignored by zone reclaim */ | ||
177 | VM_SWAP_PREFETCH=36, /* swap prefetch */ | ||
178 | VM_HARDMAPLIMIT=37, /* Make mapped a hard limit */ | ||
179 | + VM_TAIL_LARGEFILES=38, /* Read large files to lru tail */ | ||
180 | }; | ||
181 | |||
182 |