Eric Lee / linux-smarc-t335x-v3.2

Download as
Browse Code ยป

Commit f615bfca468c9b80ed2d09be5fdbaf470a32c045

Authored by Fengguang Wu
Committed by Linus Torvalds
1 parent 46fc3e7b4e
Exists in master and in 4 other branches v3.2_AM335xPSP_04.06.00.11, v3.2_NEWT335xPSP_04.06.00.11, v3.2_SBC_SMARTMEN, v3.2_SMARCT335xPSP_04.06.00.11

readahead: MIN_RA_PAGES/MAX_RA_PAGES macros 

Define two convenient macros for read-ahead:
	- MAX_RA_PAGES: rounded down counterpart of VM_MAX_READAHEAD
	- MIN_RA_PAGES: rounded _up_ counterpart of VM_MIN_READAHEAD

Note that the rounded up MIN_RA_PAGES will work flawlessly with _large_
page sizes like 64k.

Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Steven Pratt <slpratt@austin.ibm.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Showing 1 changed file with 10 additions and 2 deletions Side-by-side Diff

... ... @@ -21,8 +21,16 @@
21 21 }
22 22 EXPORT_SYMBOL(default_unplug_io_fn);
23 23  
  24 +/*
  25 + * Convienent macros for min/max read-ahead pages.
  26 + * Note that MAX_RA_PAGES is rounded down, while MIN_RA_PAGES is rounded up.
  27 + * The latter is necessary for systems with large page size(i.e. 64k).
  28 + */
  29 +#define MAX_RA_PAGES (VM_MAX_READAHEAD*1024 / PAGE_CACHE_SIZE)
  30 +#define MIN_RA_PAGES DIV_ROUND_UP(VM_MIN_READAHEAD*1024, PAGE_CACHE_SIZE)
  31 +
24 32 struct backing_dev_info default_backing_dev_info = {
25   - .ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE,
  33 + .ra_pages = MAX_RA_PAGES,
26 34 .state = 0,
27 35 .capabilities = BDI_CAP_MAP_COPY,
28 36 .unplug_io_fn = default_unplug_io_fn,
... ... @@ -51,7 +59,7 @@
51 59  
52 60 static inline unsigned long get_min_readahead(struct file_ra_state *ra)
53 61 {
54   - return (VM_MIN_READAHEAD * 1024) / PAGE_CACHE_SIZE;
  62 + return MIN_RA_PAGES;
55 63 }
56 64  
57 65 static inline void reset_ahead_window(struct file_ra_state *ra)