* About JFFS2 garbage collector.
@ 2006-03-10 10:35 Nikhil
2006-03-10 11:05 ` Artem B. Bityutskiy
0 siblings, 1 reply; 6+ messages in thread
From: Nikhil @ 2006-03-10 10:35 UTC (permalink / raw)
To: linux-mtd; +Cc: nikhils
Hi all,
I am fascinated about the JFFS3 garbage collect mechanism but before
moving to the JFFS3 garbage collection policy i wanted to analyse the
jffs2 garbage collection.
Is there any documentations as such for the JFFS2 garbage collection
policy. Plaese let me know if any. Even if there is none, i am not
hesistant to look in the code, can some one of you give me some pointers
for the same.
i would also like to kno all the instances when the GC thread gets
activated for JFFS2.
Seeking your advice, thanks for the same..
--
Thanks & Regards
Nikhil Shirodkar
Project Engineer
NISG, CDAC
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: About JFFS2 garbage collector.
2006-03-10 10:35 About JFFS2 garbage collector Nikhil
@ 2006-03-10 11:05 ` Artem B. Bityutskiy
2006-03-10 12:15 ` NIkhil Shirodkar
0 siblings, 1 reply; 6+ messages in thread
From: Artem B. Bityutskiy @ 2006-03-10 11:05 UTC (permalink / raw)
To: Nikhil; +Cc: linux-mtd
Nikhil wrote:
> Is there any documentations as such for the JFFS2 garbage collection
> policy. Plaese let me know if any. Even if there is none, i am not
> hesistant to look in the code, can some one of you give me some pointers
> for the same.
I don't think there is some documentation. JFFS2 GC policy is fairly
trivial. Just ask your questions, I'll try to answer.
--
Best Regards,
Artem B. Bityutskiy,
St.-Petersburg, Russia.
^ permalink raw reply [flat|nested] 6+ messages in thread
* RE: About JFFS2 garbage collector.
2006-03-10 11:05 ` Artem B. Bityutskiy
@ 2006-03-10 12:15 ` NIkhil Shirodkar
2006-03-10 14:50 ` Artem B. Bityutskiy
0 siblings, 1 reply; 6+ messages in thread
From: NIkhil Shirodkar @ 2006-03-10 12:15 UTC (permalink / raw)
To: Artem B. Bityutskiy; +Cc: linux-mtd
What I figured out one call jffs2_garbage_collect_pass() which initiates
garbage collection when there is not enough space to write a file. I figured
out few more instances when this got called, Let me know if this is the only
call to trigger garbage collector or are there any more calls?
Is it essential to call jffs2_garbage_collect_pass() repeatedly to get a
free jeb, or if once the jffs2_garbage_collect_pass() is called, it ensures
of making one jeb free. (barring the case when ic-->state of
INO_STATE_READING is found and the GC returns success without achieving the
desired)
I also wanted to find out _all_ other instances when the GC thread runs. Is
there any way one can force the GC thread to run like the case when, you are
not performing any I/O operations. This might be helpful to reduce the write
latency of a nearly full filesystem.
thx,
nik
NISG, CDAC
-----Original Message-----
From: Artem B. Bityutskiy [mailto:dedekind@yandex.ru]
Sent: Friday, March 10, 2006 4:35 PM
To: Nikhil
Cc: linux-mtd@lists.infradead.org
Subject: Re: About JFFS2 garbage collector.
Nikhil wrote:
> Is there any documentations as such for the JFFS2 garbage collection
> policy. Plaese let me know if any. Even if there is none, i am not
> hesistant to look in the code, can some one of you give me some pointers
> for the same.
I don't think there is some documentation. JFFS2 GC policy is fairly
trivial. Just ask your questions, I'll try to answer.
--
Best Regards,
Artem B. Bityutskiy,
St.-Petersburg, Russia.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: About JFFS2 garbage collector.
2006-03-10 12:15 ` NIkhil Shirodkar
@ 2006-03-10 14:50 ` Artem B. Bityutskiy
2006-03-10 14:51 ` Artem B. Bityutskiy
0 siblings, 1 reply; 6+ messages in thread
From: Artem B. Bityutskiy @ 2006-03-10 14:50 UTC (permalink / raw)
To: nikhils; +Cc: linux-mtd
NIkhil Shirodkar wrote:
> What I figured out one call jffs2_garbage_collect_pass() which initiates
> garbage collection when there is not enough space to write a file. I figured
> out few more instances when this got called, Let me know if this is the only
> call to trigger garbage collector or are there any more calls?
This is the only.
> Is it essential to call jffs2_garbage_collect_pass() repeatedly to get a
> free jeb, or if once the jffs2_garbage_collect_pass() is called, it ensures
> of making one jeb free. (barring the case when ic-->state of
> INO_STATE_READING is found and the GC returns success without achieving the
> desired)
One jffs2_garbage_collect_pass() is supposed to move one node (or zero
in special cases as you has specified), so you have to loop to get full
eraseblock (jeb) garbage collect-ed.
> I also wanted to find out _all_ other instances when the GC thread runs. Is
> there any way one can force the GC thread to run like the case when, you are
> not performing any I/O operations. This might be helpful to reduce the write
> latency of a nearly full filesystem.
jffs2_garbage_collect_pass() may be called by
1. GC thread
2. a writing process when there is no free space
1. is just an optimization and is run when you do not perform any I/O.
There is a threshold of free space above which GC thread do not run. You
can force it by sending a SIGHUP signal (causes one
jffs2_garbage_collect_pass() invocation.
--
Best Regards,
Artem B. Bityutskiy,
St.-Petersburg, Russia.
^ permalink raw reply [flat|nested] 6+ messages in thread
* About JFFS2 garbage collector.
@ 2006-03-10 10:35 Nikhil
0 siblings, 0 replies; 6+ messages in thread
From: Nikhil @ 2006-03-10 10:35 UTC (permalink / raw)
To: linux-mtd; +Cc: nikhils
Hi all,
I am fascinated about the JFFS3 garbage collect mechanism but before
moving to the JFFS3 garbage collection policy i wanted to analyse the
jffs2 garbage collection.
Is there any documentations as such for the JFFS2 garbage collection
policy. Plaese let me know if any. Even if there is none, i am not
hesistant to look in the code, can some one of you give me some pointers
for the same.
i would also like to kno all the instances when the GC thread gets
activated for JFFS2.
Seeking your advice, thanks for the same..
--
Thanks & Regards
Nikhil Shirodkar
Project Engineer
NISG, CDAC
^ permalink raw reply [flat|nested] 6+ messages in thread
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2006-03-10 10:35 About JFFS2 garbage collector Nikhil
2006-03-10 11:05 ` Artem B. Bityutskiy
2006-03-10 12:15 ` NIkhil Shirodkar
2006-03-10 14:50 ` Artem B. Bityutskiy
2006-03-10 14:51 ` Artem B. Bityutskiy
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2006-03-10 10:35 Nikhil
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