Re: [PATCH 1/3] xfs: add kmem allocation trace points

Brian Foster
2019-08-21T13:34:36Z

On Wed, Aug 21, 2019 at 06:38:18PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
>
> When trying to correlate XFS kernel allocations to memory reclaim
> behaviour, it is useful to know what allocations XFS is actually
> attempting. This information is not directly available from
> tracepoints in the generic memory allocation and reclaim
> tracepoints, so these new trace points provide a high level
> indication of what the XFS memory demand actually is.
>
> There is no per-filesystem context in this code, so we just trace
> the type of allocation, the size and the allocation constraints.
> The kmem code also doesn't include much of the common XFS headers,
> so there are a few definitions that need to be added to the trace
> headers and a couple of types that need to be made common to avoid
> needing to include the whole world in the kmem code.
>
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> ---
> fs/xfs/kmem.c | 11 +++++++++--
> fs/xfs/libxfs/xfs_types.h | 8 ++++++++
> fs/xfs/xfs_mount.h | 7 -------
> fs/xfs/xfs_trace.h | 33 +++++++++++++++++++++++++++++++++
> 4 files changed, 50 insertions(+), 9 deletions(-)
>
> diff --git a/fs/xfs/kmem.c b/fs/xfs/kmem.c
> index 16bb9a328678..edcf393c8fd9 100644
> --- a/fs/xfs/kmem.c
> +++ b/fs/xfs/kmem.c
...
> @@ -85,6 +91,7 @@ kmem_zone_alloc(kmem_zone_t *zone, xfs_km_flags_t flags)
> gfp_t lflags = kmem_flags_convert(flags);
> void *ptr;
>
> + trace_kmem_zone_alloc(0, flags, _RET_IP_);

You can use kmem_cache_size() to determine object size here. With that
fixed:

Reviewed-by: Brian Foster <bfoster@redhat.com>

> do {
> ptr = kmem_cache_alloc(zone, lflags);
> if (ptr || (flags & (KM_MAYFAIL|KM_NOSLEEP)))
> diff --git a/fs/xfs/libxfs/xfs_types.h b/fs/xfs/libxfs/xfs_types.h
> index 802b34cd10fe..300b3e91ca3a 100644
> --- a/fs/xfs/libxfs/xfs_types.h
> +++ b/fs/xfs/libxfs/xfs_types.h
> @@ -169,6 +169,14 @@ typedef struct xfs_bmbt_irec
> xfs_exntst_t br_state; /* extent state */
> } xfs_bmbt_irec_t;
>
> +/* per-AG block reservation types */
> +enum xfs_ag_resv_type {
> + XFS_AG_RESV_NONE = 0,
> + XFS_AG_RESV_AGFL,
> + XFS_AG_RESV_METADATA,
> + XFS_AG_RESV_RMAPBT,
> +};
> +
> /*
> * Type verifier functions
> */
> diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
> index 4adb6837439a..fdb60e09a9c5 100644
> --- a/fs/xfs/xfs_mount.h
> +++ b/fs/xfs/xfs_mount.h
> @@ -327,13 +327,6 @@ xfs_daddr_to_agbno(struct xfs_mount *mp, xfs_daddr_t d)
> }
>
> /* per-AG block reservation data structures*/
> -enum xfs_ag_resv_type {
> - XFS_AG_RESV_NONE = 0,
> - XFS_AG_RESV_AGFL,
> - XFS_AG_RESV_METADATA,
> - XFS_AG_RESV_RMAPBT,
> -};
> -
> struct xfs_ag_resv {
> /* number of blocks originally reserved here */
> xfs_extlen_t ar_orig_reserved;
> diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
> index 8094b1920eef..8bb8b4704a00 100644
> --- a/fs/xfs/xfs_trace.h
> +++ b/fs/xfs/xfs_trace.h
> @@ -23,6 +23,7 @@ struct xlog;
> struct xlog_ticket;
> struct xlog_recover;
> struct xlog_recover_item;
> +struct xlog_rec_header;
> struct xfs_buf_log_format;
> struct xfs_inode_log_format;
> struct xfs_bmbt_irec;
> @@ -30,6 +31,10 @@ struct xfs_btree_cur;
> struct xfs_refcount_irec;
> struct xfs_fsmap;
> struct xfs_rmap_irec;
> +struct xfs_icreate_log;
> +struct xfs_owner_info;
> +struct xfs_trans_res;
> +struct xfs_inobt_rec_incore;
>
> DECLARE_EVENT_CLASS(xfs_attr_list_class,
> TP_PROTO(struct xfs_attr_list_context *ctx),
> @@ -3575,6 +3580,34 @@ TRACE_EVENT(xfs_pwork_init,
> __entry->nr_threads, __entry->pid)
> )
>
> +DECLARE_EVENT_CLASS(xfs_kmem_class,
> + TP_PROTO(ssize_t size, int flags, unsigned long caller_ip),
> + TP_ARGS(size, flags, caller_ip),
> + TP_STRUCT__entry(
> + __field(ssize_t, size)
> + __field(int, flags)
> + __field(unsigned long, caller_ip)
> + ),
> + TP_fast_assign(
> + __entry->size = size;
> + __entry->flags = flags;
> + __entry->caller_ip = caller_ip;
> + ),
> + TP_printk("size %zd flags 0x%x caller %pS",
> + __entry->size,
> + __entry->flags,
> + (char *)__entry->caller_ip)
> +)
> +
> +#define DEFINE_KMEM_EVENT(name) \
> +DEFINE_EVENT(xfs_kmem_class, name, \
> + TP_PROTO(ssize_t size, int flags, unsigned long caller_ip), \
> + TP_ARGS(size, flags, caller_ip))
> +DEFINE_KMEM_EVENT(kmem_alloc);
> +DEFINE_KMEM_EVENT(kmem_alloc_large);
> +DEFINE_KMEM_EVENT(kmem_realloc);
> +DEFINE_KMEM_EVENT(kmem_zone_alloc);
> +
> #endif /* _TRACE_XFS_H */
>
> #undef TRACE_INCLUDE_PATH
> --
> 2.23.0.rc1
>