Re: [PATCH v2 1/4] bcache: finish incremental GC

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 2018/4/16 2:33 PM, tang.junhui@xxxxxxxxxx wrote:
> From: Tang Junhui <tang.junhui@xxxxxxxxxx>
> 
> 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.
> 
> Patch v2: Rename some variables and macros name as Coly suggested.
> 
> Signed-off-by: Tang Junhui <tang.junhui@xxxxxxxxxx>

Reviewed-by: Coly Li <colyli@xxxxxxx>

Thanks.

Coly Li

> ---
>  drivers/md/bcache/bcache.h  |  5 +++++
>  drivers/md/bcache/btree.c   | 15 ++++++++++++++-
>  drivers/md/bcache/request.c |  3 +++
>  3 files changed, 22 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
> index 843877e..5d52be8 100644
> --- a/drivers/md/bcache/bcache.h
> +++ b/drivers/md/bcache/bcache.h
> @@ -445,6 +445,7 @@ struct cache {
>  
>  struct gc_stat {
>  	size_t			nodes;
> +	size_t			nodes_pre;
>  	size_t			key_bytes;
>  
>  	size_t			nkeys;
> @@ -568,6 +569,10 @@ struct cache_set {
>  	 */
>  	atomic_t		rescale;
>  	/*
> +	 * used for GC, identify if any front side I/Os is inflight
> +	 */
> +	atomic_t		search_inflight;
> +	/*
>  	 * When we invalidate buckets, we use both the priority and the amount
>  	 * of good data to determine which buckets to reuse first - to weight
>  	 * those together consistently we keep track of the smallest nonzero
> diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
> index 81e8dc3..6edb00e 100644
> --- a/drivers/md/bcache/btree.c
> +++ b/drivers/md/bcache/btree.c
> @@ -90,6 +90,9 @@
>  
>  #define MAX_NEED_GC		64
>  #define MAX_SAVE_PRIO		72
> +#define MIN_GC_NODES		100
> +#define GC_SLEEP_MS		100
> +
>  
>  #define PTR_DIRTY_BIT		(((uint64_t) 1 << 36))
>  
> @@ -1581,6 +1584,13 @@ static int btree_gc_recurse(struct btree *b, struct btree_op *op,
>  		memmove(r + 1, r, sizeof(r[0]) * (GC_MERGE_NODES - 1));
>  		r->b = NULL;
>  
> +		if (atomic_read(&b->c->search_inflight) &&
> +		    gc->nodes >= gc->nodes_pre + MIN_GC_NODES) {
> +			gc->nodes_pre =  gc->nodes;
> +			ret = -EAGAIN;
> +			break;
> +		}
> +
>  		if (need_resched()) {
>  			ret = -EAGAIN;
>  			break;
> @@ -1748,7 +1758,10 @@ static void bch_btree_gc(struct cache_set *c)
>  		closure_sync(&writes);
>  		cond_resched();
>  
> -		if (ret && ret != -EAGAIN)
> +		if (ret == -EAGAIN)
> +			schedule_timeout_interruptible(msecs_to_jiffies
> +						       (GC_SLEEP_MS));
> +		else if (ret)
>  			pr_warn("gc failed!");
>  	} while (ret);
>  
> diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
> index 643c3021..a12afbc 100644
> --- a/drivers/md/bcache/request.c
> +++ b/drivers/md/bcache/request.c
> @@ -637,7 +637,9 @@ static void do_bio_hook(struct search *s, struct bio *orig_bio)
>  static void search_free(struct closure *cl)
>  {
>  	struct search *s = container_of(cl, struct search, cl);
> +
>  	bio_complete(s);
> +	atomic_dec(&s->d->c->search_inflight);
>  
>  	if (s->iop.bio)
>  		bio_put(s->iop.bio);
> @@ -655,6 +657,7 @@ static inline struct search *search_alloc(struct bio *bio,
>  
>  	closure_init(&s->cl, NULL);
>  	do_bio_hook(s, bio);
> +	atomic_inc(&d->c->search_inflight);
>  
>  	s->orig_bio		= bio;
>  	s->cache_miss		= NULL;
> 




[Index of Archives]     [Linux RAID]     [Linux SCSI]     [Linux ATA RAID]     [IDE]     [Linux Wireless]     [Linux Kernel]     [ATH6KL]     [Linux Bluetooth]     [Linux Netdev]     [Kernel Newbies]     [Security]     [Git]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Device Mapper]

  Powered by Linux