Commit 3965c9ae authored by Wanpeng Li's avatar Wanpeng Li Committed by Linus Torvalds
Browse files

mm: prepare for removal of obsolete /proc/sys/vm/nr_pdflush_threads 



Since per-BDI flusher threads were introduced in 2.6, the pdflush
mechanism is not used any more.  But the old interface exported through
/proc/sys/vm/nr_pdflush_threads still exists and is obviously useless.

For back-compatibility, printk warning information and return 2 to notify
the users that the interface is removed.

Signed-off-by: default avatarWanpeng Li <liwp@linux.vnet.ibm.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent deaf386e

Documentation/ABI/obsolete/proc-sys-vm-nr_pdflush_threads

0 → 100644
+5 −0
Original line number Diff line number Diff line 
What:		/proc/sys/vm/nr_pdflush_threads

Date:		June 2012

Contact:	Wanpeng Li <liwp@linux.vnet.ibm.com>

Description: Since pdflush is replaced by per-BDI flusher, the interface of old pdflush

             exported in /proc/sys/vm/ should be removed.

Documentation/feature-removal-schedule.txt

+8 −0
Original line number Diff line number Diff line
@@ -13,6 +13,14 @@ Who: Jim Cromie <jim.cromie@gmail.com>, Jason Baron <jbaron@redhat.com> 


---------------------------



What: /proc/sys/vm/nr_pdflush_threads

When: 2012

Why: Since pdflush is deprecated, the interface exported in /proc/sys/vm/

     should be removed.

Who: Wanpeng Li <liwp@linux.vnet.ibm.com>



---------------------------



What:	CONFIG_APM_CPU_IDLE, and its ability to call APM BIOS in idle

When:	2012

Why:	This optional sub-feature of APM is of dubious reliability,

Documentation/sysctl/vm.txt

+0 −11
Original line number Diff line number Diff line
@@ -42,7 +42,6 @@ Currently, these files are in /proc/sys/vm: 
- mmap_min_addr

- nr_hugepages

- nr_overcommit_hugepages

- nr_pdflush_threads

- nr_trim_pages         (only if CONFIG_MMU=n)

- numa_zonelist_order

- oom_dump_tasks
@@ -426,16 +425,6 @@ See Documentation/vm/hugetlbpage.txt 


==============================================================



nr_pdflush_threads



The current number of pdflush threads.  This value is read-only.

The value changes according to the number of dirty pages in the system.



When necessary, additional pdflush threads are created, one per second, up to

nr_pdflush_threads_max.



==============================================================



nr_trim_pages



This is available only on NOMMU kernels.

fs/fs-writeback.c

+0 −5
Original line number Diff line number Diff line
@@ -52,11 +52,6 @@ struct wb_writeback_work { 
	struct completion *done;	/* set if the caller waits */

};



/*

 * We don't actually have pdflush, but this one is exported though /proc...

 */

int nr_pdflush_threads;



/**

 * writeback_in_progress - determine whether there is writeback in progress

 * @bdi: the device's backing_dev_info structure.

include/linux/backing-dev.h

+3 −0
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
#include <linux/timer.h>

#include <linux/writeback.h>

#include <linux/atomic.h>

#include <linux/sysctl.h>



struct page;

struct device;
@@ -304,6 +305,8 @@ void clear_bdi_congested(struct backing_dev_info *bdi, int sync); 
void set_bdi_congested(struct backing_dev_info *bdi, int sync);

long congestion_wait(int sync, long timeout);

long wait_iff_congested(struct zone *zone, int sync, long timeout);

int pdflush_proc_obsolete(struct ctl_table *table, int write,

		void __user *buffer, size_t *lenp, loff_t *ppos);



static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)

{

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