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sunrpc: make the cache cleaner workqueue deferrable 

This patch makes the cache_cleaner workqueue deferrable, to prevent
unnecessary system wake-ups, which is very important for embedded
battery-powered devices.

do_cache_clean() is called every 30 seconds at the moment, and often
makes the system wake up from its power-save sleep state. With this
change, when the workqueue uses a deferrable timer, the
do_cache_clean() invocation will be delayed and combined with the
closest "real" wake-up. This improves the power consumption situation.

Note, I tried to create a DECLARE_DELAYED_WORK_DEFERRABLE() helper
macro, similar to DECLARE_DELAYED_WORK(), but failed because of the
way the timer wheel core stores the deferrable flag (it is the
LSBit in the time->base pointer). My attempt to define a static
variable with this bit set ended up with the "initializer element is
not constant" error.

Thus, I have to use run-time initialization, so I created a new
cache_initialize() function which is called once when sunrpc is
being initialized.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
This commit is contained in:
Artem Bityutskiy 2010-07-01 18:05:56 +03:00 committed by J. Bruce Fields
parent cba9ba4b90
commit 8eab945c56
3 changed files with 8 additions and 1 deletions
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1
include/linux/sunrpc/cache.h
View File

@ -192,6 +192,7 @@ extern int cache_check(struct cache_detail *detail,
extern void cache_flush(void);
extern void cache_purge(struct cache_detail *detail);
#define NEVER (0x7FFFFFFF)
extern void __init cache_initialize(void);
extern int cache_register(struct cache_detail *cd);
extern void cache_unregister(struct cache_detail *cd);

7
net/sunrpc/cache.c
View File

@ -320,7 +320,7 @@ static struct cache_detail *current_detail;
static int current_index;
static void do_cache_clean(struct work_struct *work);
static DECLARE_DELAYED_WORK(cache_cleaner, do_cache_clean);
static struct delayed_work cache_cleaner;
static void sunrpc_init_cache_detail(struct cache_detail *cd)
{
@ -1504,6 +1504,11 @@ static int create_cache_proc_entries(struct cache_detail *cd)
}
#endif
void __init cache_initialize(void)
{
INIT_DELAYED_WORK_DEFERRABLE(&cache_cleaner, do_cache_clean);
}
int cache_register(struct cache_detail *cd)
{
int ret;

1
net/sunrpc/sunrpc_syms.c
View File

@ -43,6 +43,7 @@ init_sunrpc(void)
#ifdef CONFIG_PROC_FS
rpc_proc_init();
#endif
cache_initialize();
cache_register(&ip_map_cache);
cache_register(&unix_gid_cache);
svc_init_xprt_sock(); /* svc sock transport */