documentation: clarify dirty_ratio and dirty_background_ratio description
Subsystems (2)
PATCH 1/1 documentation: clarify dirty_ratio and dirty_background_ratio description
The current documentation of dirty_ratio and dirty_background_ratio is a bit misleading.
In the documentation we say that they are "a percentage of total system memory", but the current page writeback policy, intead, is to apply the percentages to the dirtyable memory, that means free pages + reclaimable pages.
Better to be more explicit to clarify this concept.
--- Documentation/filesystems/proc.txt | 11 ++++++----- 1 files changed, 6 insertions(+), 5 deletions(-)
Documentation/filesystems/proc.txt +6 -5
@@ -1380,15 +1380,16 @@ causes the kernel to prefer to reclaim dentries and inodes. dirty_background_ratio ---------------------- -Contains, as a percentage of total system memory, the number of pages at which -the pdflush background writeback daemon will start writing out dirty data. +Contains, as a percentage of the dirtyable system memory (free pages + +reclaimable pages), the number of pages at which the pdflush background +writeback daemon will start writing out dirty data. dirty_ratio ----------------- -Contains, as a percentage of total system memory, the number of pages at which -a process which is generating disk writes will itself start writing out dirty -data. +Contains, as a percentage of the dirtyable system memory (free pages + +reclaimable pages), the number of pages at which a process which is generating +disk writes will itself start writing out dirty data. dirty_writeback_centisecs -------------------------
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to [email protected]. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"[email protected]"> [email protected] </a>
Quoted 11 lines
The current documentation of
dirty_ratioanddirty_background_ratiois a bit misleading.In the documentation we say that they are "a percentage of total system memory", but the current page writeback policy, intead, is to apply the percentages to the dirtyable memory, that means free pages + reclaimable pages.
Better to be more explicit to clarify this concept.
Signed-off-by Andrea Righi <[email protected]>
looks good to me.
Quoted 20 lines
--- Documentation/filesystems/proc.txt | 11 ++++++----- 1 files changed, 6 insertions(+), 5 deletions(-)Documentation/filesystems/proc.txt +3
-2@@ -1380,15 +1380,16 @@ causes the kernel to prefer to reclaim dentries and inodes. dirty_background_ratio ---------------------- -Contains, as a percentage of total system memory, the number of pages at which -the pdflush background writeback daemon will start writing out dirty data. +Contains, as a percentage of the dirtyable system memory (free pages + +reclaimable pages), the number of pages at which the pdflush background +writeback daemon will start writing out dirty data. dirty_ratio -----------------
Documentation/filesystems/proc.txt causes the kernel to prefer to reclaim dentries and inodes. · line 1395
Quoted 10 lines
Documentation/filesystems/proc.txt +3
-3-Contains, as a percentage of total system memory, the number of pages at which -a process which is generating disk writes will itself start writing out dirty -data. +Contains, as a percentage of the dirtyable system memory (free pages + +reclaimable pages), the number of pages at which a process which is generating +disk writes will itself start writing out dirty data. dirty_writeback_centisecs -------------------------
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to [email protected]. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"[email protected]"> [email protected] </a>
Quoted 8 lines · On Wed, 08 Oct 2008 12:52:28 +0200 Andrea Righi <[email protected]> wrote:
The current documentation of
dirty_ratioanddirty_background_ratiois a bit misleading.In the documentation we say that they are "a percentage of total system memory", but the current page writeback policy, intead, is to apply the percentages to the dirtyable memory, that means free pages + reclaimable pages.
Right.
Quoted 3 lines
Better to be more explicit to clarify this concept.
Signed-off-by Andrea Righi <[email protected]>
But I wonder "reclaimable memory" seems to be a difficult word for users....
"free pages + mapped pages + file cache, not including locked page and HugePage" ?
Anyway,
Quoted 21 lines
--- Documentation/filesystems/proc.txt | 11 ++++++----- 1 files changed, 6 insertions(+), 5 deletions(-)Documentation/filesystems/proc.txt +3
-2@@ -1380,15 +1380,16 @@ causes the kernel to prefer to reclaim dentries and inodes. dirty_background_ratio ---------------------- -Contains, as a percentage of total system memory, the number of pages at which -the pdflush background writeback daemon will start writing out dirty data. +Contains, as a percentage of the dirtyable system memory (free pages + +reclaimable pages), the number of pages at which the pdflush background +writeback daemon will start writing out dirty data. dirty_ratio -----------------
Documentation/filesystems/proc.txt causes the kernel to prefer to reclaim dentries and inodes. · line 1395
Quoted 10 lines
Documentation/filesystems/proc.txt +3
-3-Contains, as a percentage of total system memory, the number of pages at which -a process which is generating disk writes will itself start writing out dirty -data. +Contains, as a percentage of the dirtyable system memory (free pages + +reclaimable pages), the number of pages at which a process which is generating +disk writes will itself start writing out dirty data. dirty_writeback_centisecs -------------------------
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to [email protected]. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"[email protected]"> [email protected] </a>
Quoted 15 lines · KAMEZAWA Hiroyuki
Quoted 8 lines · On Wed, 08 Oct 2008 12:52:28 +0200 Andrea Righi <[email protected]> wrote:
The current documentation of
dirty_ratioanddirty_background_ratiois a bit misleading.In the documentation we say that they are "a percentage of total system memory", but the current page writeback policy, intead, is to apply the percentages to the dirtyable memory, that means free pages + reclaimable pages.
Right.
Quoted 2 lines
Better to be more explicit to clarify this concept.
Quoted 8 lines
Quoted 1 line
Signed-off-by Andrea Righi <[email protected]>But I wonder "reclaimable memory" seems to be a difficult word for users....
"free pages + mapped pages + file cache, not including locked page and HugePage" ?
Anyway,
Sounds better. I'll add these details and post a new patch.
Thanks,
-Andrea
Quoted 29 lines
Quoted 29 lines
--- Documentation/filesystems/proc.txt | 11 ++++++----- 1 files changed, 6 insertions(+), 5 deletions(-)Documentation/filesystems/proc.txt +6
-5@@ -1380,15 +1380,16 @@ causes the kernel to prefer to reclaim dentries and inodes. dirty_background_ratio ---------------------- -Contains, as a percentage of total system memory, the number of pages at which -the pdflush background writeback daemon will start writing out dirty data. +Contains, as a percentage of the dirtyable system memory (free pages + +reclaimable pages), the number of pages at which the pdflush background +writeback daemon will start writing out dirty data. dirty_ratio ----------------- -Contains, as a percentage of total system memory, the number of pages at which -a process which is generating disk writes will itself start writing out dirty -data. +Contains, as a percentage of the dirtyable system memory (free pages + +reclaimable pages), the number of pages at which a process which is generating +disk writes will itself start writing out dirty data.
Quoted 3 lines
Documentation/filesystems/proc.txt causes the kernel to prefer to reclaim dentries and inodes. · line 1395
Quoted 3 lines
Documentation/filesystems/proc.txt +0
-0dirty_writeback_centisecs -------------------------
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to [email protected]. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"[email protected]"> [email protected] </a>
PATCH 1/1 documentation: clarify dirty_ratio and dirty_background_ratio description (v2)
In reply to KAMEZAWA HiroyukiThe current documentation of dirty_ratio and dirty_background_ratio is a bit misleading.
In the documentation we say that they are "a percentage of total system memory", but the current page writeback policy, intead, is to apply the percentages to the dirtyable memory, that means free pages + reclaimable pages.
Better to be more explicit to clarify this concept.
--- Documentation/filesystems/proc.txt | 13 ++++++++----- 1 files changed, 8 insertions(+), 5 deletions(-)
Documentation/filesystems/proc.txt +8 -5
@@ -1380,15 +1380,18 @@ causes the kernel to prefer to reclaim dentries and inodes. dirty_background_ratio ---------------------- -Contains, as a percentage of total system memory, the number of pages at which -the pdflush background writeback daemon will start writing out dirty data. +Contains, as a percentage of the dirtyable system memory (free pages + mapped +pages + file cache, not including locked pages and HugePages), the number of +pages at which the pdflush background writeback daemon will start writing out +dirty data. dirty_ratio ----------------- -Contains, as a percentage of total system memory, the number of pages at which -a process which is generating disk writes will itself start writing out dirty -data. +Contains, as a percentage of the dirtyable system memory (free pages + mapped +pages + file cache, not including locked pages and HugePages), the number of +pages at which a process which is generating disk writes will itself start +writing out dirty data. dirty_writeback_centisecs -------------------------
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to [email protected]. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"[email protected]"> [email protected] </a>