Re: [PATCH] f2fs: avoid unnecessary fg_gc

[heyunlei <heyunlei@huawei.com>]

Hi Jaegeuk,

On 2017/2/27 9:59, Hou Pengyang wrote:
> We use has_not_enough_free_secs to check if there are enough free segments,
>
>          (free_sections(sbi) + freed) <=
>             (node_secs + 2 * dent_secs + imeta_secs +
>                      reserved_sections(sbi) + needed);

Now node SSR is enable, how can we change this condition simply as:

	(free_sections(sbi) + freed) <= reserved_sections(sbi)

If dirty node pages can find SSR segment, write it in SSR mode,

or it will consume free segments, and then we do FG_GC.



Another thing is that each process has a chance to do FG_GC, it's no problem

for all normal processes, but may be not a good thing for a process within

certain limits such as lower priority, with bound cpu to do FG_GC. Maybe it

will block system for a long time. So what can we do to improve this?

Thanks.



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