/[pkg-src]/trunk/kernel26-magellan/patches-2.6.17-r6/0027-2.6.17-mm-filesize_dependant_lru_cache_add.patch |
Contents of /trunk/kernel26-magellan/patches-2.6.17-r6/0027-2.6.17-mm-filesize_dependant_lru_cache_add.patch
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Revision 105 -
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Sun Mar 11 16:17:56 2007 UTC (17 years, 6 months ago) by niro
File size: 7698 byte(s)
Sun Mar 11 16:17:56 2007 UTC (17 years, 6 months ago) by niro
File size: 7698 byte(s)
2.6.17-magellan-r6
1 | 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 | include/linux/writeback.h | 2 + |
16 | kernel/sysctl.c | 9 +++++++ |
17 | mm/filemap.c | 47 +++++++++++++++++++++++++++++++++++-- |
18 | mm/page-writeback.c | 2 - |
19 | mm/swap.c | 3 -- |
20 | 8 files changed, 68 insertions(+), 6 deletions(-) |
21 | |
22 | Index: linux-ck-dev/include/linux/writeback.h |
23 | =================================================================== |
24 | --- linux-ck-dev.orig/include/linux/writeback.h 2006-06-18 15:20:10.000000000 +1000 |
25 | +++ linux-ck-dev/include/linux/writeback.h 2006-06-18 15:25:25.000000000 +1000 |
26 | @@ -85,6 +85,8 @@ void laptop_io_completion(void); |
27 | void laptop_sync_completion(void); |
28 | void throttle_vm_writeout(void); |
29 | |
30 | +extern long total_pages; |
31 | + |
32 | /* These are exported to sysctl. */ |
33 | extern int dirty_background_ratio; |
34 | extern int vm_dirty_ratio; |
35 | Index: linux-ck-dev/mm/filemap.c |
36 | =================================================================== |
37 | --- linux-ck-dev.orig/mm/filemap.c 2006-06-18 15:20:10.000000000 +1000 |
38 | +++ linux-ck-dev/mm/filemap.c 2006-06-18 15:25:25.000000000 +1000 |
39 | @@ -434,6 +434,16 @@ int add_to_page_cache_lru(struct page *p |
40 | return ret; |
41 | } |
42 | |
43 | +int add_to_page_cache_lru_tail(struct page *page, |
44 | + struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask) |
45 | +{ |
46 | + int ret = add_to_page_cache(page, mapping, offset, gfp_mask); |
47 | + |
48 | + if (ret == 0) |
49 | + lru_cache_add_tail(page); |
50 | + return ret; |
51 | +} |
52 | + |
53 | #ifdef CONFIG_NUMA |
54 | struct page *page_cache_alloc(struct address_space *x) |
55 | { |
56 | @@ -783,6 +793,28 @@ grab_cache_page_nowait(struct address_sp |
57 | EXPORT_SYMBOL(grab_cache_page_nowait); |
58 | |
59 | /* |
60 | + * Sysctl which determines whether we should read from large files to the |
61 | + * tail of the inactive lru list. |
62 | + */ |
63 | +int vm_tail_largefiles __read_mostly = 1; |
64 | + |
65 | +/* |
66 | + * This examines how large in pages a file size is and returns 1 if it is |
67 | + * more than half the unmapped ram. Avoid doing read_page_state which is |
68 | + * expensive unless we already know it is likely to be large enough. |
69 | + */ |
70 | +static int large_isize(unsigned long nr_pages) |
71 | +{ |
72 | + if (nr_pages * 6 > total_pages) { |
73 | + unsigned long unmapped_ram = total_pages - read_page_state(nr_mapped); |
74 | + |
75 | + if (nr_pages * 2 > unmapped_ram) |
76 | + return 1; |
77 | + } |
78 | + return 0; |
79 | +} |
80 | + |
81 | +/* |
82 | * This is a generic file read routine, and uses the |
83 | * mapping->a_ops->readpage() function for the actual low-level |
84 | * stuff. |
85 | @@ -982,8 +1014,19 @@ no_cached_page: |
86 | goto out; |
87 | } |
88 | } |
89 | - error = add_to_page_cache_lru(cached_page, mapping, |
90 | - index, GFP_KERNEL); |
91 | + |
92 | + /* |
93 | + * If we know the file is large we add the pages read to the |
94 | + * end of the lru as we're unlikely to be able to cache the |
95 | + * whole file in ram so make those pages the first to be |
96 | + * dropped if not referenced soon. |
97 | + */ |
98 | + if (vm_tail_largefiles && large_isize(end_index)) |
99 | + error = add_to_page_cache_lru_tail(cached_page, |
100 | + mapping, index, GFP_KERNEL); |
101 | + else |
102 | + error = add_to_page_cache_lru(cached_page, mapping, |
103 | + index, GFP_KERNEL); |
104 | if (error) { |
105 | if (error == -EEXIST) |
106 | goto find_page; |
107 | Index: linux-ck-dev/mm/page-writeback.c |
108 | =================================================================== |
109 | --- linux-ck-dev.orig/mm/page-writeback.c 2006-06-18 15:25:22.000000000 +1000 |
110 | +++ linux-ck-dev/mm/page-writeback.c 2006-06-18 15:25:25.000000000 +1000 |
111 | @@ -45,7 +45,7 @@ |
112 | */ |
113 | static long ratelimit_pages = 32; |
114 | |
115 | -static long total_pages; /* The total number of pages in the machine. */ |
116 | +long total_pages __read_mostly; /* The total number of pages in the machine. */ |
117 | static int dirty_exceeded __cacheline_aligned_in_smp; /* Dirty mem may be over limit */ |
118 | |
119 | /* |
120 | Index: linux-ck-dev/mm/swap.c |
121 | =================================================================== |
122 | --- linux-ck-dev.orig/mm/swap.c 2006-06-18 15:24:48.000000000 +1000 |
123 | +++ linux-ck-dev/mm/swap.c 2006-06-18 15:25:25.000000000 +1000 |
124 | @@ -416,8 +416,7 @@ void __pagevec_lru_add_active(struct pag |
125 | |
126 | /* |
127 | * Function used uniquely to put pages back to the lru at the end of the |
128 | - * inactive list to preserve the lru order. Currently only used by swap |
129 | - * prefetch. |
130 | + * inactive list to preserve the lru order. |
131 | */ |
132 | void fastcall lru_cache_add_tail(struct page *page) |
133 | { |
134 | Index: linux-ck-dev/include/linux/sysctl.h |
135 | =================================================================== |
136 | --- linux-ck-dev.orig/include/linux/sysctl.h 2006-06-18 15:24:58.000000000 +1000 |
137 | +++ linux-ck-dev/include/linux/sysctl.h 2006-06-18 15:25:25.000000000 +1000 |
138 | @@ -191,6 +191,7 @@ enum |
139 | VM_ZONE_RECLAIM_INTERVAL=32, /* time period to wait after reclaim failure */ |
140 | VM_SWAP_PREFETCH=33, /* swap prefetch */ |
141 | VM_HARDMAPLIMIT=34, /* Make mapped a hard limit */ |
142 | + VM_TAIL_LARGEFILES=35, /* Read large files to lru tail */ |
143 | }; |
144 | |
145 | |
146 | Index: linux-ck-dev/kernel/sysctl.c |
147 | =================================================================== |
148 | --- linux-ck-dev.orig/kernel/sysctl.c 2006-06-18 15:24:58.000000000 +1000 |
149 | +++ linux-ck-dev/kernel/sysctl.c 2006-06-18 15:25:25.000000000 +1000 |
150 | @@ -73,6 +73,7 @@ extern int printk_ratelimit_burst; |
151 | extern int pid_max_min, pid_max_max; |
152 | extern int sysctl_drop_caches; |
153 | extern int percpu_pagelist_fraction; |
154 | +extern int vm_tail_largefiles; |
155 | |
156 | #if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86) |
157 | int unknown_nmi_panic; |
158 | @@ -809,6 +810,14 @@ static ctl_table vm_table[] = { |
159 | .mode = 0644, |
160 | .proc_handler = &proc_dointvec, |
161 | }, |
162 | + { |
163 | + .ctl_name = VM_TAIL_LARGEFILES, |
164 | + .procname = "tail_largefiles", |
165 | + .data = &vm_tail_largefiles, |
166 | + .maxlen = sizeof(int), |
167 | + .mode = 0644, |
168 | + .proc_handler = &proc_dointvec, |
169 | + }, |
170 | #ifdef CONFIG_HUGETLB_PAGE |
171 | { |
172 | .ctl_name = VM_HUGETLB_PAGES, |
173 | Index: linux-ck-dev/Documentation/filesystems/proc.txt |
174 | =================================================================== |
175 | --- linux-ck-dev.orig/Documentation/filesystems/proc.txt 2006-06-18 15:20:10.000000000 +1000 |
176 | +++ linux-ck-dev/Documentation/filesystems/proc.txt 2006-06-18 15:25:25.000000000 +1000 |
177 | @@ -1318,6 +1318,14 @@ To free pagecache, dentries and inodes: |
178 | As this is a non-destructive operation and dirty objects are not freeable, the |
179 | user should run `sync' first. |
180 | |
181 | +tail_largefiles |
182 | +--------------- |
183 | + |
184 | +When enabled reads from large files to the tail end of the inactive lru list. |
185 | +This means that any cache from reading large files is dropped very quickly, |
186 | +preventing loss of mapped ram and useful pagecache when large files are read. |
187 | +This does, however, make caching less effective when working with large files. |
188 | + |
189 | |
190 | 2.5 /proc/sys/dev - Device specific parameters |
191 | ---------------------------------------------- |
192 | Index: linux-ck-dev/Documentation/sysctl/vm.txt |
193 | =================================================================== |
194 | --- linux-ck-dev.orig/Documentation/sysctl/vm.txt 2006-06-18 15:24:58.000000000 +1000 |
195 | +++ linux-ck-dev/Documentation/sysctl/vm.txt 2006-06-18 15:25:25.000000000 +1000 |
196 | @@ -37,7 +37,7 @@ Currently, these files are in /proc/sys/ |
197 | |
198 | dirty_ratio, dirty_background_ratio, dirty_expire_centisecs, |
199 | dirty_writeback_centisecs, vfs_cache_pressure, laptop_mode, |
200 | -block_dump, swap_token_timeout, drop-caches: |
201 | +block_dump, swap_token_timeout, drop-caches, tail_largefiles: |
202 | |
203 | See Documentation/filesystems/proc.txt |
204 |