Hi Ryusuke,
On 2014-02-05 03:16, Andreas Rohner wrote:
> This patch adds an additional parameter min_reclaimable_blks to
> the nilfs_reclaim_params structure. This parameter specifies the
> minimum number of reclaimable blocks in a segment, before it can be
> cleaned. If a segment is below this threshold, it is considered to
> be not worth cleaning, because all the live blocks would need to be
> moved to a new segment, which is expensive, and the number of
> reclaimable blocks is too low. But it is still necessary to update
> the segment usage information to turn the old segment into a new
> one.
>
> This is basically a shortcut to cleaning the segment. It is still
> necessary to read the segment summary information, but the writing
> of the live blocks can be skipped if it's not worth it.
>
> This optimization can be enabled and disabled by the
> use_set_suinfo switch in the configuration file. If the kernel
> doesn't support the set_suinfo ioctl it returns the error
> number ENOTTY, which also permanently disables the optimization.
>
> Signed-off-by: Andreas Rohner <andreas.rohner@xxxxxxx>
> ---
> include/nilfs_gc.h | 7 +++---
> lib/gc.c | 63 +++++++++++++++++++++++++++++++++++++++++++++---
> sbin/cleanerd/cleanerd.c | 18 +++++++++++---
> 3 files changed, 77 insertions(+), 11 deletions(-)
>
> diff --git a/include/nilfs_gc.h b/include/nilfs_gc.h
> index e49cbf4..1196c55 100644
> --- a/include/nilfs_gc.h
> +++ b/include/nilfs_gc.h
> @@ -17,18 +17,19 @@
> /* flags for nilfs_reclaim_params struct */
> #define NILFS_RECLAIM_PARAM_PROTSEQ (1UL << 0)
> #define NILFS_RECLAIM_PARAM_PROTCNO (1UL << 1)
> -#define __NR_NILFS_RECLAIM_PARAMS 2
> +#define NILFS_RECLAIM_PARAM_DEFERRABLE (1UL << 2)
> +#define __NR_NILFS_RECLAIM_PARAMS 3
>
> /**
> * struct nilfs_reclaim_params - structure to specify GC parameters
> * @flags: flags of valid fields
> - * @reserved: padding bytes
> + * @min_reclaimable_blks: minimum number of reclaimable blocks
> * @protseq: start of sequence number of protected segments
> * @protcno: start number of checkpoint to be protected
> */
> struct nilfs_reclaim_params {
> unsigned long flags;
> - unsigned long reserved;
> + unsigned long min_reclaimable_blks;
> __u64 protseq;
> nilfs_cno_t protcno;
> };
> diff --git a/lib/gc.c b/lib/gc.c
> index 71c7307..4aa6a2c 100644
> --- a/lib/gc.c
> +++ b/lib/gc.c
> @@ -29,6 +29,10 @@
> #include <syslog.h>
> #endif /* HAVE_SYSLOG_H */
>
> +#if HAVE_SYS_TIME_H
> +#include <sys/time.h>
> +#endif /* HAVE_SYS_TIME */
> +
> #include <errno.h>
> #include <assert.h>
> #include <stdarg.h>
> @@ -617,8 +621,11 @@ int nilfs_xreclaim_segment(struct nilfs *nilfs,
> struct nilfs_vector *vdescv, *bdescv, *periodv, *vblocknrv;
> sigset_t sigset, oldset, waitset;
> nilfs_cno_t protcno;
> - ssize_t n, ret = -1;
> + ssize_t n, i, ret = -1;
> size_t nblocks;
> + __u32 reclaimable_blocks;
> + struct nilfs_suinfo_update *supv;
> + struct timeval tv;
>
> if (!(params->flags & NILFS_RECLAIM_PARAM_PROTSEQ) ||
> (params->flags & (~0UL << __NR_NILFS_RECLAIM_PARAMS))) {
> @@ -703,13 +710,16 @@ int nilfs_xreclaim_segment(struct nilfs *nilfs,
> if (ret < 0)
> goto out_lock;
>
> + reclaimable_blocks = (nilfs_get_blocks_per_segment(nilfs) * n) -
> + (nilfs_vector_get_size(vdescv) +
> + nilfs_vector_get_size(bdescv));
> +
> if (stat) {
> stat->live_pblks = nilfs_vector_get_size(bdescv);
> stat->defunct_pblks = nblocks - stat->live_pblks;
>
> stat->live_blks = stat->live_vblks + stat->live_pblks;
> - stat->defunct_blks = n * nilfs_get_blocks_per_segment(nilfs) -
> - stat->live_blks;
> + stat->defunct_blks = reclaimable_blocks;
> }
> if (dryrun)
> goto out_lock;
> @@ -725,6 +735,51 @@ int nilfs_xreclaim_segment(struct nilfs *nilfs,
> goto out_lock;
> }
>
> + /* if there are less reclaimable blocks than the
> + * minimal threshold try to update suinfo
> + * instead of cleaning */
> + if ((params->flags & NILFS_RECLAIM_PARAM_DEFERRABLE) &&
> + reclaimable_blocks < params->min_reclaimable_blks * n) {
> + if (stat)
> + stat->deferred_segs = n;
> +
> + ret = gettimeofday(&tv, NULL);
> + if (ret < 0)
> + goto out_lock;
> +
> + supv = malloc(sizeof(struct nilfs_suinfo_update) * n);
> + if (supv == NULL) {
> + ret = -1;
> + goto out_lock;
> + }
I have already changed nilfs_xreclaim_segments to use
nilfs_vector_create for supv instead of malloc and free directly. Don't
know why I originally used malloc, since the rest of the function uses
the nilfs_vector API.
Regards,
Andreas Rohner
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