[PATCH net-next v3 0/2] net/smc: introduce ringbufs usage statistics

[PATCH net-next v3 0/2] net/smc: introduce ringbufs usage statistics

[Wen Gu]

Currently, we have histograms that show the sizes of ringbufs that ever
used by SMC connections. However, they are always incremental and since
SMC allows the reuse of ringbufs, we cannot know the actual amount of
ringbufs being allocated or actively used.

So this patch set introduces statistics for the amount of ringbufs that
actually allocated by link group and actively used by connections of a
certain net namespace, so that we can react based on these memory usage
information, e.g. active fallback to TCP.

With appropriate adaptations of smc-tools, we can obtain these ringbufs
usage information:

$ smcr -d linkgroup
LG-ID    : 00000500
LG-Role  : SERV
LG-Type  : ASYML
VLAN     : 0
PNET-ID  :
Version  : 1
Conns    : 0
Sndbuf   : 12910592 B    <-
RMB      : 12910592 B    <-

or

$ smcr -d stats
[...]
RX Stats
  Data transmitted (Bytes)      869225943 (869.2M)
  Total requests                 18494479
  Buffer usage  (Bytes)          12910592 (12.31M)  <-
  [...]

TX Stats
  Data transmitted (Bytes)    12760884405 (12.76G)
  Total requests                 36988338
  Buffer usage  (Bytes)          12910592 (12.31M)  <-
  [...]
[...]


Change log:
v3->v2
- use new helper nla_put_uint() instead of nla_put_u64_64bit().

v2->v1
https://lore.kernel.org/r/20240807075939.57882-1-guwen@linux.alibaba.com/
- remove inline keyword in .c files.
- use local variable in macros to avoid potential side effects.

v1
https://lore.kernel.org/r/20240805090551.80786-1-guwen@linux.alibaba.com/

Wen Gu (2):
  net/smc: introduce statistics for allocated ringbufs of link group
  net/smc: introduce statistics for ringbufs usage of net namespace

 include/uapi/linux/smc.h |  6 ++++
 net/smc/smc_core.c       | 68 +++++++++++++++++++++++++++++++++-------
 net/smc/smc_core.h       |  2 ++
 net/smc/smc_stats.c      |  6 ++++
 net/smc/smc_stats.h      | 28 +++++++++++------
 5 files changed, 90 insertions(+), 20 deletions(-)

-- 
2.32.0.3.g01195cf9f

[PATCH net-next v3 1/2] net/smc: introduce statistics for allocated ringbufs of link group

[Wen Gu]

Currently we have the statistics on sndbuf/RMB sizes of all connections
that have ever been on the link group, namely smc_stats_memsize. However
these statistics are incremental and since the ringbufs of link group
are allowed to be reused, we cannot know the actual allocated buffers
through these. So here introduces the statistic on actual allocated
ringbufs of the link group, it will be incremented when a new ringbuf is
added into buf_list and decremented when it is deleted from buf_list.

Signed-off-by: Wen Gu <guwen@linux.alibaba.com>
---
 include/uapi/linux/smc.h |  4 ++++
 net/smc/smc_core.c       | 46 ++++++++++++++++++++++++++++++++++++----
 net/smc/smc_core.h       |  2 ++
 3 files changed, 48 insertions(+), 4 deletions(-)

diff --git a/include/uapi/linux/smc.h b/include/uapi/linux/smc.h
index b531e3ef011a..9b74ef79070a 100644
--- a/include/uapi/linux/smc.h
+++ b/include/uapi/linux/smc.h
@@ -127,6 +127,8 @@ enum {
 	SMC_NLA_LGR_R_NET_COOKIE,	/* u64 */
 	SMC_NLA_LGR_R_PAD,		/* flag */
 	SMC_NLA_LGR_R_BUF_TYPE,		/* u8 */
+	SMC_NLA_LGR_R_SNDBUF_ALLOC,	/* uint */
+	SMC_NLA_LGR_R_RMB_ALLOC,	/* uint */
 	__SMC_NLA_LGR_R_MAX,
 	SMC_NLA_LGR_R_MAX = __SMC_NLA_LGR_R_MAX - 1
 };
@@ -162,6 +164,8 @@ enum {
 	SMC_NLA_LGR_D_V2_COMMON,	/* nest */
 	SMC_NLA_LGR_D_EXT_GID,		/* u64 */
 	SMC_NLA_LGR_D_PEER_EXT_GID,	/* u64 */
+	SMC_NLA_LGR_D_SNDBUF_ALLOC,	/* uint */
+	SMC_NLA_LGR_D_DMB_ALLOC,	/* uint */
 	__SMC_NLA_LGR_D_MAX,
 	SMC_NLA_LGR_D_MAX = __SMC_NLA_LGR_D_MAX - 1
 };
diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
index 71fb334d8234..8dcf1c7f1526 100644
--- a/net/smc/smc_core.c
+++ b/net/smc/smc_core.c
@@ -221,6 +221,35 @@ static void smc_lgr_unregister_conn(struct smc_connection *conn)
 	write_unlock_bh(&lgr->conns_lock);
 }
 
+static void smc_lgr_buf_list_add(struct smc_link_group *lgr,
+				 bool is_rmb,
+				 struct list_head *buf_list,
+				 struct smc_buf_desc *buf_desc)
+{
+	list_add(&buf_desc->list, buf_list);
+	if (is_rmb) {
+		lgr->alloc_rmbs += buf_desc->len;
+		lgr->alloc_rmbs +=
+			lgr->is_smcd ? sizeof(struct smcd_cdc_msg) : 0;
+	} else {
+		lgr->alloc_sndbufs += buf_desc->len;
+	}
+}
+
+static void smc_lgr_buf_list_del(struct smc_link_group *lgr,
+				 bool is_rmb,
+				 struct smc_buf_desc *buf_desc)
+{
+	list_del(&buf_desc->list);
+	if (is_rmb) {
+		lgr->alloc_rmbs -= buf_desc->len;
+		lgr->alloc_rmbs -=
+			lgr->is_smcd ? sizeof(struct smcd_cdc_msg) : 0;
+	} else {
+		lgr->alloc_sndbufs -= buf_desc->len;
+	}
+}
+
 int smc_nl_get_sys_info(struct sk_buff *skb, struct netlink_callback *cb)
 {
 	struct smc_nl_dmp_ctx *cb_ctx = smc_nl_dmp_ctx(cb);
@@ -363,6 +392,10 @@ static int smc_nl_fill_lgr(struct smc_link_group *lgr,
 	smc_target[SMC_MAX_PNETID_LEN] = 0;
 	if (nla_put_string(skb, SMC_NLA_LGR_R_PNETID, smc_target))
 		goto errattr;
+	if (nla_put_uint(skb, SMC_NLA_LGR_R_SNDBUF_ALLOC, lgr->alloc_sndbufs))
+		goto errattr;
+	if (nla_put_uint(skb, SMC_NLA_LGR_R_RMB_ALLOC, lgr->alloc_rmbs))
+		goto errattr;
 	if (lgr->smc_version > SMC_V1) {
 		v2_attrs = nla_nest_start(skb, SMC_NLA_LGR_R_V2_COMMON);
 		if (!v2_attrs)
@@ -541,6 +574,10 @@ static int smc_nl_fill_smcd_lgr(struct smc_link_group *lgr,
 		goto errattr;
 	if (nla_put_u32(skb, SMC_NLA_LGR_D_CHID, smc_ism_get_chid(lgr->smcd)))
 		goto errattr;
+	if (nla_put_uint(skb, SMC_NLA_LGR_D_SNDBUF_ALLOC, lgr->alloc_sndbufs))
+		goto errattr;
+	if (nla_put_uint(skb, SMC_NLA_LGR_D_DMB_ALLOC, lgr->alloc_rmbs))
+		goto errattr;
 	memcpy(smc_pnet, lgr->smcd->pnetid, SMC_MAX_PNETID_LEN);
 	smc_pnet[SMC_MAX_PNETID_LEN] = 0;
 	if (nla_put_string(skb, SMC_NLA_LGR_D_PNETID, smc_pnet))
@@ -1138,7 +1175,7 @@ static void smcr_buf_unuse(struct smc_buf_desc *buf_desc, bool is_rmb,
 		lock = is_rmb ? &lgr->rmbs_lock :
 				&lgr->sndbufs_lock;
 		down_write(lock);
-		list_del(&buf_desc->list);
+		smc_lgr_buf_list_del(lgr, is_rmb, buf_desc);
 		up_write(lock);
 
 		smc_buf_free(lgr, is_rmb, buf_desc);
@@ -1377,7 +1414,7 @@ static void __smc_lgr_free_bufs(struct smc_link_group *lgr, bool is_rmb)
 			buf_list = &lgr->sndbufs[i];
 		list_for_each_entry_safe(buf_desc, bf_desc, buf_list,
 					 list) {
-			list_del(&buf_desc->list);
+			smc_lgr_buf_list_del(lgr, is_rmb, buf_desc);
 			smc_buf_free(lgr, is_rmb, buf_desc);
 		}
 	}
@@ -2414,7 +2451,7 @@ static int __smc_buf_create(struct smc_sock *smc, bool is_smcd, bool is_rmb)
 		SMC_STAT_RMB_SIZE(smc, is_smcd, is_rmb, bufsize);
 		buf_desc->used = 1;
 		down_write(lock);
-		list_add(&buf_desc->list, buf_list);
+		smc_lgr_buf_list_add(lgr, is_rmb, buf_list, buf_desc);
 		up_write(lock);
 		break; /* found */
 	}
@@ -2496,7 +2533,8 @@ int smc_buf_create(struct smc_sock *smc, bool is_smcd)
 	rc = __smc_buf_create(smc, is_smcd, true);
 	if (rc && smc->conn.sndbuf_desc) {
 		down_write(&smc->conn.lgr->sndbufs_lock);
-		list_del(&smc->conn.sndbuf_desc->list);
+		smc_lgr_buf_list_del(smc->conn.lgr, false,
+				     smc->conn.sndbuf_desc);
 		up_write(&smc->conn.lgr->sndbufs_lock);
 		smc_buf_free(smc->conn.lgr, false, smc->conn.sndbuf_desc);
 		smc->conn.sndbuf_desc = NULL;
diff --git a/net/smc/smc_core.h b/net/smc/smc_core.h
index d93cf51dbd7c..0db4e5f79ac4 100644
--- a/net/smc/smc_core.h
+++ b/net/smc/smc_core.h
@@ -281,6 +281,8 @@ struct smc_link_group {
 	struct rw_semaphore	sndbufs_lock;	/* protects tx buffers */
 	struct list_head	rmbs[SMC_RMBE_SIZES];	/* rx buffers */
 	struct rw_semaphore	rmbs_lock;	/* protects rx buffers */
+	u64			alloc_sndbufs;	/* stats of tx buffers */
+	u64			alloc_rmbs;	/* stats of rx buffers */
 
 	u8			id[SMC_LGR_ID_SIZE];	/* unique lgr id */
 	struct delayed_work	free_work;	/* delayed freeing of an lgr */
-- 
2.32.0.3.g01195cf9f

[PATCH net-next v3 2/2] net/smc: introduce statistics for ringbufs usage of net namespace

[Wen Gu]

The buffer size histograms in smc_stats, namely rx/tx_rmbsize, record
the sizes of ringbufs for all connections that have ever appeared in
the net namespace. They are incremental and we cannot know the actual
ringbufs usage from these. So here introduces statistics for current
ringbufs usage of existing smc connections in the net namespace into
smc_stats, it will be incremented when new connection uses a ringbuf
and decremented when the ringbuf is unused.

Signed-off-by: Wen Gu <guwen@linux.alibaba.com>
---
 include/uapi/linux/smc.h |  2 ++
 net/smc/smc_core.c       | 22 +++++++++++++++-------
 net/smc/smc_stats.c      |  6 ++++++
 net/smc/smc_stats.h      | 28 +++++++++++++++++++---------
 4 files changed, 42 insertions(+), 16 deletions(-)

diff --git a/include/uapi/linux/smc.h b/include/uapi/linux/smc.h
index 9b74ef79070a..1f58cb0c266b 100644
--- a/include/uapi/linux/smc.h
+++ b/include/uapi/linux/smc.h
@@ -253,6 +253,8 @@ enum {
 	SMC_NLA_STATS_T_TX_BYTES,	/* u64 */
 	SMC_NLA_STATS_T_RX_CNT,		/* u64 */
 	SMC_NLA_STATS_T_TX_CNT,		/* u64 */
+	SMC_NLA_STATS_T_RX_RMB_USAGE,	/* uint */
+	SMC_NLA_STATS_T_TX_RMB_USAGE,	/* uint */
 	__SMC_NLA_STATS_T_MAX,
 	SMC_NLA_STATS_T_MAX = __SMC_NLA_STATS_T_MAX - 1
 };
diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
index 8dcf1c7f1526..4e694860ece4 100644
--- a/net/smc/smc_core.c
+++ b/net/smc/smc_core.c
@@ -1203,22 +1203,30 @@ static void smcd_buf_detach(struct smc_connection *conn)
 static void smc_buf_unuse(struct smc_connection *conn,
 			  struct smc_link_group *lgr)
 {
+	struct smc_sock *smc = container_of(conn, struct smc_sock, conn);
+	bool is_smcd = lgr->is_smcd;
+	int bufsize;
+
 	if (conn->sndbuf_desc) {
-		if (!lgr->is_smcd && conn->sndbuf_desc->is_vm) {
+		bufsize = conn->sndbuf_desc->len;
+		if (!is_smcd && conn->sndbuf_desc->is_vm) {
 			smcr_buf_unuse(conn->sndbuf_desc, false, lgr);
 		} else {
-			memzero_explicit(conn->sndbuf_desc->cpu_addr, conn->sndbuf_desc->len);
+			memzero_explicit(conn->sndbuf_desc->cpu_addr, bufsize);
 			WRITE_ONCE(conn->sndbuf_desc->used, 0);
 		}
+		SMC_STAT_RMB_SIZE(smc, is_smcd, false, false, bufsize);
 	}
 	if (conn->rmb_desc) {
-		if (!lgr->is_smcd) {
+		bufsize = conn->rmb_desc->len;
+		if (!is_smcd) {
 			smcr_buf_unuse(conn->rmb_desc, true, lgr);
 		} else {
-			memzero_explicit(conn->rmb_desc->cpu_addr,
-					 conn->rmb_desc->len + sizeof(struct smcd_cdc_msg));
+			bufsize += sizeof(struct smcd_cdc_msg);
+			memzero_explicit(conn->rmb_desc->cpu_addr, bufsize);
 			WRITE_ONCE(conn->rmb_desc->used, 0);
 		}
+		SMC_STAT_RMB_SIZE(smc, is_smcd, true, false, bufsize);
 	}
 }
 
@@ -2427,7 +2435,7 @@ static int __smc_buf_create(struct smc_sock *smc, bool is_smcd, bool is_rmb)
 		buf_desc = smc_buf_get_slot(bufsize_comp, lock, buf_list);
 		if (buf_desc) {
 			buf_desc->is_dma_need_sync = 0;
-			SMC_STAT_RMB_SIZE(smc, is_smcd, is_rmb, bufsize);
+			SMC_STAT_RMB_SIZE(smc, is_smcd, is_rmb, true, bufsize);
 			SMC_STAT_BUF_REUSE(smc, is_smcd, is_rmb);
 			break; /* found reusable slot */
 		}
@@ -2448,7 +2456,7 @@ static int __smc_buf_create(struct smc_sock *smc, bool is_smcd, bool is_rmb)
 		}
 
 		SMC_STAT_RMB_ALLOC(smc, is_smcd, is_rmb);
-		SMC_STAT_RMB_SIZE(smc, is_smcd, is_rmb, bufsize);
+		SMC_STAT_RMB_SIZE(smc, is_smcd, is_rmb, true, bufsize);
 		buf_desc->used = 1;
 		down_write(lock);
 		smc_lgr_buf_list_add(lgr, is_rmb, buf_list, buf_desc);
diff --git a/net/smc/smc_stats.c b/net/smc/smc_stats.c
index ca14c0f3a07d..e71b17d1e21c 100644
--- a/net/smc/smc_stats.c
+++ b/net/smc/smc_stats.c
@@ -218,6 +218,12 @@ static int smc_nl_fill_stats_tech_data(struct sk_buff *skb,
 			      smc_tech->tx_bytes,
 			      SMC_NLA_STATS_PAD))
 		goto errattr;
+	if (nla_put_uint(skb, SMC_NLA_STATS_T_RX_RMB_USAGE,
+			 smc_tech->rx_rmbuse))
+		goto errattr;
+	if (nla_put_uint(skb, SMC_NLA_STATS_T_TX_RMB_USAGE,
+			 smc_tech->tx_rmbuse))
+		goto errattr;
 	if (nla_put_u64_64bit(skb, SMC_NLA_STATS_T_RX_CNT,
 			      smc_tech->rx_cnt,
 			      SMC_NLA_STATS_PAD))
diff --git a/net/smc/smc_stats.h b/net/smc/smc_stats.h
index 9d32058db2b5..6ac465380431 100644
--- a/net/smc/smc_stats.h
+++ b/net/smc/smc_stats.h
@@ -79,6 +79,8 @@ struct smc_stats_tech {
 	u64			tx_bytes;
 	u64			rx_cnt;
 	u64			tx_cnt;
+	u64			rx_rmbuse;
+	u64			tx_rmbuse;
 };
 
 struct smc_stats {
@@ -135,38 +137,46 @@ do { \
 } \
 while (0)
 
-#define SMC_STAT_RMB_SIZE_SUB(_smc_stats, _tech, k, _len) \
+#define SMC_STAT_RMB_SIZE_SUB(_smc_stats, _tech, k, _is_add, _len) \
 do { \
+	typeof(_smc_stats) stats = (_smc_stats); \
+	typeof(_is_add) is_a = (_is_add); \
 	typeof(_len) _l = (_len); \
 	typeof(_tech) t = (_tech); \
 	int _pos; \
 	int m = SMC_BUF_MAX - 1; \
 	if (_l <= 0) \
 		break; \
-	_pos = fls((_l - 1) >> 13); \
-	_pos = (_pos <= m) ? _pos : m; \
-	this_cpu_inc((*(_smc_stats)).smc[t].k ## _rmbsize.buf[_pos]); \
+	if (is_a) { \
+		_pos = fls((_l - 1) >> 13); \
+		_pos = (_pos <= m) ? _pos : m; \
+		this_cpu_inc((*stats).smc[t].k ## _rmbsize.buf[_pos]); \
+		this_cpu_add((*stats).smc[t].k ## _rmbuse, _l); \
+	} else { \
+		this_cpu_sub((*stats).smc[t].k ## _rmbuse, _l); \
+	} \
 } \
 while (0)
 
 #define SMC_STAT_RMB_SUB(_smc_stats, type, t, key) \
 	this_cpu_inc((*(_smc_stats)).smc[t].rmb ## _ ## key.type ## _cnt)
 
-#define SMC_STAT_RMB_SIZE(_smc, _is_smcd, _is_rx, _len) \
+#define SMC_STAT_RMB_SIZE(_smc, _is_smcd, _is_rx, _is_add, _len) \
 do { \
 	struct net *_net = sock_net(&(_smc)->sk); \
 	struct smc_stats __percpu *_smc_stats = _net->smc.smc_stats; \
+	typeof(_is_add) is_add = (_is_add); \
 	typeof(_is_smcd) is_d = (_is_smcd); \
 	typeof(_is_rx) is_r = (_is_rx); \
 	typeof(_len) l = (_len); \
 	if ((is_d) && (is_r)) \
-		SMC_STAT_RMB_SIZE_SUB(_smc_stats, SMC_TYPE_D, rx, l); \
+		SMC_STAT_RMB_SIZE_SUB(_smc_stats, SMC_TYPE_D, rx, is_add, l); \
 	if ((is_d) && !(is_r)) \
-		SMC_STAT_RMB_SIZE_SUB(_smc_stats, SMC_TYPE_D, tx, l); \
+		SMC_STAT_RMB_SIZE_SUB(_smc_stats, SMC_TYPE_D, tx, is_add, l); \
 	if (!(is_d) && (is_r)) \
-		SMC_STAT_RMB_SIZE_SUB(_smc_stats, SMC_TYPE_R, rx, l); \
+		SMC_STAT_RMB_SIZE_SUB(_smc_stats, SMC_TYPE_R, rx, is_add, l); \
 	if (!(is_d) && !(is_r)) \
-		SMC_STAT_RMB_SIZE_SUB(_smc_stats, SMC_TYPE_R, tx, l); \
+		SMC_STAT_RMB_SIZE_SUB(_smc_stats, SMC_TYPE_R, tx, is_add, l); \
 } \
 while (0)
 
-- 
2.32.0.3.g01195cf9f

Re: [PATCH net-next v3 0/2] net/smc: introduce ringbufs usage statistics

[Wen Gu]

On 2024/8/14 21:08, Wen Gu wrote:
> Currently, we have histograms that show the sizes of ringbufs that ever
> used by SMC connections. However, they are always incremental and since
> SMC allows the reuse of ringbufs, we cannot know the actual amount of
> ringbufs being allocated or actively used.
> 
> So this patch set introduces statistics for the amount of ringbufs that
> actually allocated by link group and actively used by connections of a
> certain net namespace, so that we can react based on these memory usage
> information, e.g. active fallback to TCP.
> 
> With appropriate adaptations of smc-tools, we can obtain these ringbufs
> usage information:
> 
> $ smcr -d linkgroup
> LG-ID    : 00000500
> LG-Role  : SERV
> LG-Type  : ASYML
> VLAN     : 0
> PNET-ID  :
> Version  : 1
> Conns    : 0
> Sndbuf   : 12910592 B    <-
> RMB      : 12910592 B    <-
> 
> or
> 
> $ smcr -d stats
> [...]
> RX Stats
>    Data transmitted (Bytes)      869225943 (869.2M)
>    Total requests                 18494479
>    Buffer usage  (Bytes)          12910592 (12.31M)  <-
>    [...]
> 
> TX Stats
>    Data transmitted (Bytes)    12760884405 (12.76G)
>    Total requests                 36988338
>    Buffer usage  (Bytes)          12910592 (12.31M)  <-
>    [...]
> [...]
> 

FYI, The corresponding smc-tools modification has been submitted.

https://github.com/ibm-s390-linux/smc-tools/pull/11

Thanks!

Re: [PATCH net-next v3 0/2] net/smc: introduce ringbufs usage statistics

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (main)
by Paolo Abeni <pabeni@redhat.com>:

On Wed, 14 Aug 2024 21:08:25 +0800 you wrote:
> Currently, we have histograms that show the sizes of ringbufs that ever
> used by SMC connections. However, they are always incremental and since
> SMC allows the reuse of ringbufs, we cannot know the actual amount of
> ringbufs being allocated or actively used.
> 
> So this patch set introduces statistics for the amount of ringbufs that
> actually allocated by link group and actively used by connections of a
> certain net namespace, so that we can react based on these memory usage
> information, e.g. active fallback to TCP.
> 
> [...]

Here is the summary with links:
  - [net-next,v3,1/2] net/smc: introduce statistics for allocated ringbufs of link group
    https://git.kernel.org/netdev/net-next/c/d386d59b7c1a
  - [net-next,v3,2/2] net/smc: introduce statistics for ringbufs usage of net namespace
    https://git.kernel.org/netdev/net-next/c/e0d103542b06

You are awesome, thank you!
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