Re: [RFC PATCH v3] ceph: ceph: add remote object copies to fs client metrics

From: Jeff Layton
Date: Thu Oct 28 2021 - 08:41:57 EST

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In reply to: Luís Henriques: "[RFC PATCH v3] ceph: ceph: add remote object copies to fs client metrics"
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On Thu, 2021-10-28 at 12:48 +0100, Luís Henriques wrote:
> This patch adds latency and size metrics for remote object copies
> operations ("copyfrom"). For now, these metrics will be available on the
> client only, they won't be sent to the MDS.
>
> Cc: Patrick Donnelly <pdonnell@xxxxxxxxxx>
> Signed-off-by: Luís Henriques <lhenriques@xxxxxxx>
> ---
> This patch is still an RFC because it is... ugly. Although it now
> provides nice values (latency and size) using the metrics infrastructure,
> it actually needs to extend the ceph_osdc_copy_from() function to add 2
> extra args! That's because we need to get the timestamps stored in
> ceph_osd_request, which is handled within that function.
>
> The alternative is to ignore those timestamps and collect new ones in
> ceph_do_objects_copy():
>
> start_req = ktime_get();
> ceph_osdc_copy_from(...);
> end_req = ktime_get();
>
> These would be more coarse-grained, of course. Any other suggestions?
>

Not really. It is definitely ugly, I'll grant you that though...

The cleaner method might be to just inline ceph_osdc_copy_from in
ceph_do_objects_copy so that you deal with the req in there.

> Cheers,
> --
> Luís
>
> fs/ceph/debugfs.c               | 19 ++++++++++++++++++
> fs/ceph/file.c                  | 7 ++++++-
> fs/ceph/metric.c                | 35 +++++++++++++++++++++++++++++++++
> fs/ceph/metric.h                | 14 +++++++++++++
> include/linux/ceph/osd_client.h | 3 ++-
> net/ceph/osd_client.c           | 8 ++++++--
> 6 files changed, 82 insertions(+), 4 deletions(-)
>
> diff --git a/fs/ceph/debugfs.c b/fs/ceph/debugfs.c
> index 55426514491b..b657170d6bc3 100644
> --- a/fs/ceph/debugfs.c
> +++ b/fs/ceph/debugfs.c
> @@ -203,6 +203,16 @@ static int metrics_latency_show(struct seq_file *s, void *p)
> spin_unlock(&m->metadata_metric_lock);
> CEPH_LAT_METRIC_SHOW("metadata", total, avg, min, max, sq);
>
> + spin_lock(&m->copyfrom_metric_lock);
> + total = m->total_copyfrom;
> + sum = m->copyfrom_latency_sum;
> + avg = total > 0 ? DIV64_U64_ROUND_CLOSEST(sum, total) : 0;
> + min = m->copyfrom_latency_min;
> + max = m->copyfrom_latency_max;
> + sq = m->copyfrom_latency_sq_sum;
> + spin_unlock(&m->copyfrom_metric_lock);
> + CEPH_LAT_METRIC_SHOW("copyfrom", total, avg, min, max, sq);
> +
> return 0;
> }
>
> @@ -234,6 +244,15 @@ static int metrics_size_show(struct seq_file *s, void *p)
> spin_unlock(&m->write_metric_lock);
> CEPH_SZ_METRIC_SHOW("write", total, avg_sz, min_sz, max_sz, sum_sz);
>
> + spin_lock(&m->copyfrom_metric_lock);
> + total = m->total_copyfrom;
> + sum_sz = m->copyfrom_size_sum;
> + avg_sz = total > 0 ? DIV64_U64_ROUND_CLOSEST(sum_sz, total) : 0;
> + min_sz = m->copyfrom_size_min;
> + max_sz = m->copyfrom_size_max;
> + spin_unlock(&m->copyfrom_metric_lock);
> + CEPH_SZ_METRIC_SHOW("copyfrom", total, avg_sz, min_sz, max_sz, sum_sz);
> +
> return 0;
> }
>
> diff --git a/fs/ceph/file.c b/fs/ceph/file.c
> index e61018d9764e..d1139bbcd58d 100644
> --- a/fs/ceph/file.c
> +++ b/fs/ceph/file.c
> @@ -2208,6 +2208,7 @@ static ssize_t ceph_do_objects_copy(struct ceph_inode_info *src_ci, u64 *src_off
> struct ceph_object_locator src_oloc, dst_oloc;
> struct ceph_object_id src_oid, dst_oid;
> size_t bytes = 0;
> + ktime_t start_req, end_req;
> u64 src_objnum, src_objoff, dst_objnum, dst_objoff;
> u32 src_objlen, dst_objlen;
> u32 object_size = src_ci->i_layout.object_size;
> @@ -2242,7 +2243,11 @@ static ssize_t ceph_do_objects_copy(struct ceph_inode_info *src_ci, u64 *src_off
> CEPH_OSD_OP_FLAG_FADVISE_DONTNEED,
> dst_ci->i_truncate_seq,
> dst_ci->i_truncate_size,
> - CEPH_OSD_COPY_FROM_FLAG_TRUNCATE_SEQ);
> + CEPH_OSD_COPY_FROM_FLAG_TRUNCATE_SEQ,
> + &start_req, &end_req);
> + ceph_update_copyfrom_metrics(&fsc->mdsc->metric,
> +      start_req, end_req,
> +      object_size, ret);
> if (ret) {
> if (ret == -EOPNOTSUPP) {
> fsc->have_copy_from2 = false;
> diff --git a/fs/ceph/metric.c b/fs/ceph/metric.c
> index 04d5df29bbbf..94e7f8fd34d6 100644
> --- a/fs/ceph/metric.c
> +++ b/fs/ceph/metric.c
> @@ -270,6 +270,16 @@ int ceph_metric_init(struct ceph_client_metric *m)
> m->total_metadatas = 0;
> m->metadata_latency_sum = 0;
>
> + spin_lock_init(&m->copyfrom_metric_lock);
> + m->copyfrom_latency_sq_sum = 0;
> + m->copyfrom_latency_min = KTIME_MAX;
> + m->copyfrom_latency_max = 0;
> + m->total_copyfrom = 0;
> + m->copyfrom_latency_sum = 0;
> + m->copyfrom_size_min = U64_MAX;
> + m->copyfrom_size_max = 0;
> + m->copyfrom_size_sum = 0;
> +
> atomic64_set(&m->opened_files, 0);
> ret = percpu_counter_init(&m->opened_inodes, 0, GFP_KERNEL);
> if (ret)
> @@ -408,3 +418,28 @@ void ceph_update_metadata_metrics(struct ceph_client_metric *m,
>        &m->metadata_latency_sq_sum, lat);
> spin_unlock(&m->metadata_metric_lock);
> }
> +
> +void ceph_update_copyfrom_metrics(struct ceph_client_metric *m,
> + ktime_t r_start, ktime_t r_end,
> + unsigned int size, int rc)
> +{
> + ktime_t lat = ktime_sub(r_end, r_start);
> + ktime_t total;
> +
> + if (unlikely(rc && rc != -ETIMEDOUT))
> + return;
> +
> + spin_lock(&m->copyfrom_metric_lock);
> + total = ++m->total_copyfrom;
> + m->copyfrom_size_sum += size;
> + m->copyfrom_latency_sum += lat;
> + METRIC_UPDATE_MIN_MAX(m->copyfrom_size_min,
> +       m->copyfrom_size_max,
> +       size);
> + METRIC_UPDATE_MIN_MAX(m->copyfrom_latency_min,
> +       m->copyfrom_latency_max,
> +       lat);
> + __update_stdev(total, m->copyfrom_latency_sum,
> +        &m->copyfrom_latency_sq_sum, lat);
> + spin_unlock(&m->copyfrom_metric_lock);
> +}
> diff --git a/fs/ceph/metric.h b/fs/ceph/metric.h
> index 0133955a3c6a..c95517c7c77b 100644
> --- a/fs/ceph/metric.h
> +++ b/fs/ceph/metric.h
> @@ -162,6 +162,16 @@ struct ceph_client_metric {
> ktime_t metadata_latency_min;
> ktime_t metadata_latency_max;
>
> + spinlock_t copyfrom_metric_lock;
> + u64 total_copyfrom;
> + u64 copyfrom_size_sum;
> + u64 copyfrom_size_min;
> + u64 copyfrom_size_max;
> + ktime_t copyfrom_latency_sum;
> + ktime_t copyfrom_latency_sq_sum;
> + ktime_t copyfrom_latency_min;
> + ktime_t copyfrom_latency_max;
> +

Not a comment about your patch, specifically, but we have a lot of
copy/pasted code to deal with different parts of ceph_client_metric.

It might be nice to eventually turn each of the read/write/copy metric
blocks in this struct into an array, and collapse a lot of the other
helper functions together.

If you feel like doing that cleanup, I'd be happy to review. Otherwise,
I'll plan to look at it in the near future.

> /* The total number of directories and files that are opened */
> atomic64_t opened_files;
>
> @@ -204,4 +214,8 @@ extern void ceph_update_write_metrics(struct ceph_client_metric *m,
> extern void ceph_update_metadata_metrics(struct ceph_client_metric *m,
>          ktime_t r_start, ktime_t r_end,
> int rc);
> +extern void ceph_update_copyfrom_metrics(struct ceph_client_metric *m,
> + ktime_t r_start, ktime_t r_end,
> + unsigned int size, int rc);
> +
> #endif /* _FS_CEPH_MDS_METRIC_H */
> diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h
> index 83fa08a06507..d282c7531a3f 100644
> --- a/include/linux/ceph/osd_client.h
> +++ b/include/linux/ceph/osd_client.h
> @@ -524,7 +524,8 @@ int ceph_osdc_copy_from(struct ceph_osd_client *osdc,
> struct ceph_object_locator *dst_oloc,
> u32 dst_fadvise_flags,
> u32 truncate_seq, u64 truncate_size,
> - u8 copy_from_flags);
> + u8 copy_from_flags,
> + ktime_t *start_req, ktime_t *end_req);
>
> /* watch/notify */
> struct ceph_osd_linger_request *
> diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
> index ff8624a7c964..74ffe6240b07 100644
> --- a/net/ceph/osd_client.c
> +++ b/net/ceph/osd_client.c
> @@ -5356,7 +5356,8 @@ int ceph_osdc_copy_from(struct ceph_osd_client *osdc,
> struct ceph_object_locator *dst_oloc,
> u32 dst_fadvise_flags,
> u32 truncate_seq, u64 truncate_size,
> - u8 copy_from_flags)
> + u8 copy_from_flags,
> + ktime_t *start_req, ktime_t *end_req)
> {
> struct ceph_osd_request *req;
> int ret;
> @@ -5364,6 +5365,8 @@ int ceph_osdc_copy_from(struct ceph_osd_client *osdc,
> req = ceph_osdc_alloc_request(osdc, NULL, 1, false, GFP_KERNEL);
> if (!req)
> return -ENOMEM;
> + *start_req = 0;
> + *end_req = 0;
>
> req->r_flags = CEPH_OSD_FLAG_WRITE;
>
> @@ -5383,7 +5386,8 @@ int ceph_osdc_copy_from(struct ceph_osd_client *osdc,
>
> ceph_osdc_start_request(osdc, req, false);
> ret = ceph_osdc_wait_request(osdc, req);
> -
> + *start_req = req->r_start_latency;
> + *end_req = req->r_end_latency;
> out:
> ceph_osdc_put_request(req);
> return ret;

--
Jeff Layton <jlayton@xxxxxxxxxx>

Next message: Jiasheng Jiang: "[PATCH v4] cpumask: Fix implicit type conversion"
Previous message: Mukunda,Vijendar: "Re: [PATCH RESEND] ASoC: fix unmet dependencies on GPIOLIB for SND_SOC_DMIC"
In reply to: Luís Henriques: "[RFC PATCH v3] ceph: ceph: add remote object copies to fs client metrics"
Next in thread: Luís Henriques: "Re: [RFC PATCH v3] ceph: ceph: add remote object copies to fs client metrics"
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