On 29/01/2018 7:58 PM, tang.junhui@zte.com.cn wrote:

From: Tang Junhui <redacted>

In GC thread, we record the latest GC key in gc_done, which is expected
to be used for incremental GC, but in currently code, we didn't realize
it. When GC runs, front side IO would be blocked until the GC over, it
would be a long time if there is a lot of btree nodes.

This patch realizes incremental GC, the main ideal is that, when there
are front side I/Os, after GC some nodes (100), we stop GC, release locker
of the btree node, and go to process the front side I/Os for some times
(100 ms), then go back to GC again.

By this patch, when we doing GC, I/Os are not blocked all the time, and
there is no obvious I/Os zero jump problem any more.

Signed-off-by: Tang Junhui <redacted>

Hi Junhui,

It sounds great :-) Currently I am not very familiar with gc code, I
need some time to understand how bcache GC works before providing my
feedback. Please give me some time, I hope I am able to provide my
comment after Chinese Spring Festival.

Hope other people may have a look before I am able to.

Thanks.

Coly Li



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