Re: [f2fs-dev] [PATCH] f2fs: remove unneed reada during build free nids
On 2018/2/11 9:55, heyunlei wrote:
>
>
>> -Original Message-
>> From: Chao Yu [mailto:c...@kernel.org]
>> Sent: Friday, February 09, 2018 9:37 PM
>> To: heyunlei; jaeg...@kernel.org; Yuchao (T);
>> linux-f2fs-devel@lists.sourceforge.net
>> Subject: Re: [f2fs-dev] [PATCH] f2fs: remove unneed reada during build free
>> nids
>>
>> On 2018/2/9 11:58, Yunlei He wrote:
>>> This patch remove unneed reada during build free nids.
>>> If few nids left, three will introduce a lot of no hit
>>> read io.
>>
>> I guess it is due to be lack of commit c1fe3e981440 ("Revert "f2fs:
>> reuse nids more aggressively""), before that commit, we will update
>> .next_scan_nid randomly instead of updating it ascendingly, then
>> during __build_free_nids we may readahead NAT pages starting from
>> random position.
>
> I think commit c1fe3e981440 will reduce fragment of nat area, it
> will locate all used nids at the left head of nat area, which I think
> will do benefit to WA ?
Yup, IMO, it can reduce WA. ;)
Also, there is another patch intends to reduce WA by adjusting allocation
policy of free nid.
FYI
https://patchwork.kernel.org/patch/10084653/
>
> e.g, if we have used 1 nids, which will hold 1/455 blocks at least.
> Without this commit, the blocks taken for nids will expansion, may be 1
> blocks in the worst case, at this time, if we update node info, we will
> produce
> more nat IOs?
That's right.
Thanks,
>
>>
>> Could try that commit to check IO again?
>>
>> Thanks,
--
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Re: [f2fs-dev] [PATCH] f2fs: remove unneed reada during build free nids
>-Original Message-
>From: Chao Yu [mailto:c...@kernel.org]
>Sent: Friday, February 09, 2018 9:37 PM
>To: heyunlei; jaeg...@kernel.org; Yuchao (T);
>linux-f2fs-devel@lists.sourceforge.net
>Subject: Re: [f2fs-dev] [PATCH] f2fs: remove unneed reada during build free
>nids
>
>On 2018/2/9 11:58, Yunlei He wrote:
>> This patch remove unneed reada during build free nids.
>> If few nids left, three will introduce a lot of no hit
>> read io.
>
>I guess it is due to be lack of commit c1fe3e981440 ("Revert "f2fs:
>reuse nids more aggressively""), before that commit, we will update
>.next_scan_nid randomly instead of updating it ascendingly, then
>during __build_free_nids we may readahead NAT pages starting from
>random position.
I think commit c1fe3e981440 will reduce fragment of nat area, it
will locate all used nids at the left head of nat area, which I think
will do benefit to WA ?
e.g, if we have used 1 nids, which will hold 1/455 blocks at least.
Without this commit, the blocks taken for nids will expansion, may be 1
blocks in the worst case, at this time, if we update node info, we will produce
more nat IOs?
>
>Could try that commit to check IO again?
>
>Thanks,
--
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engaging tech sites, Slashdot.org! http://sdm.link/slashdot
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Re: [f2fs-dev] [PATCH] f2fs: remove unneed reada during build free nids
On 2018/2/9 11:58, Yunlei He wrote:
> This patch remove unneed reada during build free nids.
> If few nids left, three will introduce a lot of no hit
> read io.
I guess it is due to be lack of commit c1fe3e981440 ("Revert "f2fs:
reuse nids more aggressively""), before that commit, we will update
.next_scan_nid randomly instead of updating it ascendingly, then
during __build_free_nids we may readahead NAT pages starting from
random position.
Could try that commit to check IO again?
Thanks,
--
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
___
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