* [PATCH net v3 1/2] net/smc: Fix setsockopt and sysctl to specify same buffer size again
2023-08-04 17:06 [PATCH net v3 0/2] net/smc: Fix effective buffer size Gerd Bayer
@ 2023-08-04 17:06 ` Gerd Bayer
2023-08-04 17:06 ` [PATCH net v3 2/2] net/smc: Use correct buffer sizes when switching between TCP and SMC Gerd Bayer
2023-08-09 10:30 ` [PATCH net v3 0/2] net/smc: Fix effective buffer size patchwork-bot+netdevbpf
2 siblings, 0 replies; 4+ messages in thread
From: Gerd Bayer @ 2023-08-04 17:06 UTC (permalink / raw)
To: Wenjia Zhang, Jan Karcher, Tony Lu, Paolo Abeni
Cc: Karsten Graul, D . Wythe, Wen Gu, David S . Miller, Eric Dumazet,
Jakub Kicinski, linux-s390, netdev, linux-kernel
Commit 0227f058aa29 ("net/smc: Unbind r/w buffer size from clcsock
and make them tunable") introduced the net.smc.rmem and net.smc.wmem
sysctls to specify the size of buffers to be used for SMC type
connections. This created a regression for users that specified the
buffer size via setsockopt() as the effective buffer size was now
doubled.
Re-introduce the division by 2 in the SMC buffer create code and level
this out by duplicating the net.smc.[rw]mem values used for initializing
sk_rcvbuf/sk_sndbuf at socket creation time. This gives users of both
methods (setsockopt or sysctl) the effective buffer size that they
expect.
Initialize net.smc.[rw]mem from its own constant of 64kB, respectively.
Internal performance tests show that this value is a good compromise
between throughput/latency and memory consumption. Also, this decouples
it from any tuning that was done to net.ipv4.tcp_[rw]mem[1] before the
module for SMC protocol was loaded. Check that no more than INT_MAX / 2
is assigned to net.smc.[rw]mem, in order to avoid any overflow condition
when that is doubled for use in sk_sndbuf or sk_rcvbuf.
While at it, drop the confusing sk_buf_size variable from
__smc_buf_create and name "compressed" buffer size variables more
consistently.
Background:
Before the commit mentioned above, SMC's buffer allocator in
__smc_buf_create() always used half of the sockets' sk_rcvbuf/sk_sndbuf
value as initial value to search for appropriate buffers. If the search
resorted to using a bigger buffer when all buffers of the specified
size were busy, the duplicate of the used effective buffer size is
stored back to sk_rcvbuf/sk_sndbuf.
When available, buffers of exactly the size that a user had specified as
input to setsockopt() were used, despite setsockopt()'s documentation in
"man 7 socket" talking of a mandatory duplication:
[...]
SO_SNDBUF
Sets or gets the maximum socket send buffer in bytes.
The kernel doubles this value (to allow space for book‐
keeping overhead) when it is set using setsockopt(2),
and this doubled value is returned by getsockopt(2).
The default value is set by the
/proc/sys/net/core/wmem_default file and the maximum
allowed value is set by the /proc/sys/net/core/wmem_max
file. The minimum (doubled) value for this option is
2048.
[...]
Fixes: 0227f058aa29 ("net/smc: Unbind r/w buffer size from clcsock and make them tunable")
Co-developed-by: Jan Karcher <jaka@linux.ibm.com>
Signed-off-by: Jan Karcher <jaka@linux.ibm.com>
Reviewed-by: Wenjia Zhang <wenjia@linux.ibm.com>
Reviewed-by: Tony Lu <tonylu@linux.alibaba.com>
Signed-off-by: Gerd Bayer <gbayer@linux.ibm.com>
---
net/smc/af_smc.c | 4 ++--
net/smc/smc.h | 2 +-
net/smc/smc_clc.c | 4 ++--
net/smc/smc_core.c | 25 ++++++++++++-------------
net/smc/smc_sysctl.c | 10 ++++++++--
5 files changed, 25 insertions(+), 20 deletions(-)
diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index 0c013d2b5d8f..5b878e523abf 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -378,8 +378,8 @@ static struct sock *smc_sock_alloc(struct net *net, struct socket *sock,
sk->sk_state = SMC_INIT;
sk->sk_destruct = smc_destruct;
sk->sk_protocol = protocol;
- WRITE_ONCE(sk->sk_sndbuf, READ_ONCE(net->smc.sysctl_wmem));
- WRITE_ONCE(sk->sk_rcvbuf, READ_ONCE(net->smc.sysctl_rmem));
+ WRITE_ONCE(sk->sk_sndbuf, 2 * READ_ONCE(net->smc.sysctl_wmem));
+ WRITE_ONCE(sk->sk_rcvbuf, 2 * READ_ONCE(net->smc.sysctl_rmem));
smc = smc_sk(sk);
INIT_WORK(&smc->tcp_listen_work, smc_tcp_listen_work);
INIT_WORK(&smc->connect_work, smc_connect_work);
diff --git a/net/smc/smc.h b/net/smc/smc.h
index 2eeea4cdc718..1f2b912c43d1 100644
--- a/net/smc/smc.h
+++ b/net/smc/smc.h
@@ -161,7 +161,7 @@ struct smc_connection {
struct smc_buf_desc *sndbuf_desc; /* send buffer descriptor */
struct smc_buf_desc *rmb_desc; /* RMBE descriptor */
- int rmbe_size_short;/* compressed notation */
+ int rmbe_size_comp; /* compressed notation */
int rmbe_update_limit;
/* lower limit for consumer
* cursor update
diff --git a/net/smc/smc_clc.c b/net/smc/smc_clc.c
index b9b8b07aa702..c90d9e5dda54 100644
--- a/net/smc/smc_clc.c
+++ b/net/smc/smc_clc.c
@@ -1007,7 +1007,7 @@ static int smc_clc_send_confirm_accept(struct smc_sock *smc,
clc->d0.gid =
conn->lgr->smcd->ops->get_local_gid(conn->lgr->smcd);
clc->d0.token = conn->rmb_desc->token;
- clc->d0.dmbe_size = conn->rmbe_size_short;
+ clc->d0.dmbe_size = conn->rmbe_size_comp;
clc->d0.dmbe_idx = 0;
memcpy(&clc->d0.linkid, conn->lgr->id, SMC_LGR_ID_SIZE);
if (version == SMC_V1) {
@@ -1050,7 +1050,7 @@ static int smc_clc_send_confirm_accept(struct smc_sock *smc,
clc->r0.qp_mtu = min(link->path_mtu, link->peer_mtu);
break;
}
- clc->r0.rmbe_size = conn->rmbe_size_short;
+ clc->r0.rmbe_size = conn->rmbe_size_comp;
clc->r0.rmb_dma_addr = conn->rmb_desc->is_vm ?
cpu_to_be64((uintptr_t)conn->rmb_desc->cpu_addr) :
cpu_to_be64((u64)sg_dma_address
diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
index 3f465faf2b68..6b78075404d7 100644
--- a/net/smc/smc_core.c
+++ b/net/smc/smc_core.c
@@ -2309,31 +2309,30 @@ static int __smc_buf_create(struct smc_sock *smc, bool is_smcd, bool is_rmb)
struct smc_connection *conn = &smc->conn;
struct smc_link_group *lgr = conn->lgr;
struct list_head *buf_list;
- int bufsize, bufsize_short;
+ int bufsize, bufsize_comp;
struct rw_semaphore *lock; /* lock buffer list */
bool is_dgraded = false;
- int sk_buf_size;
if (is_rmb)
/* use socket recv buffer size (w/o overhead) as start value */
- sk_buf_size = smc->sk.sk_rcvbuf;
+ bufsize = smc->sk.sk_rcvbuf / 2;
else
/* use socket send buffer size (w/o overhead) as start value */
- sk_buf_size = smc->sk.sk_sndbuf;
+ bufsize = smc->sk.sk_sndbuf / 2;
- for (bufsize_short = smc_compress_bufsize(sk_buf_size, is_smcd, is_rmb);
- bufsize_short >= 0; bufsize_short--) {
+ for (bufsize_comp = smc_compress_bufsize(bufsize, is_smcd, is_rmb);
+ bufsize_comp >= 0; bufsize_comp--) {
if (is_rmb) {
lock = &lgr->rmbs_lock;
- buf_list = &lgr->rmbs[bufsize_short];
+ buf_list = &lgr->rmbs[bufsize_comp];
} else {
lock = &lgr->sndbufs_lock;
- buf_list = &lgr->sndbufs[bufsize_short];
+ buf_list = &lgr->sndbufs[bufsize_comp];
}
- bufsize = smc_uncompress_bufsize(bufsize_short);
+ bufsize = smc_uncompress_bufsize(bufsize_comp);
/* check for reusable slot in the link group */
- buf_desc = smc_buf_get_slot(bufsize_short, lock, buf_list);
+ 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);
@@ -2377,8 +2376,8 @@ static int __smc_buf_create(struct smc_sock *smc, bool is_smcd, bool is_rmb)
if (is_rmb) {
conn->rmb_desc = buf_desc;
- conn->rmbe_size_short = bufsize_short;
- smc->sk.sk_rcvbuf = bufsize;
+ conn->rmbe_size_comp = bufsize_comp;
+ smc->sk.sk_rcvbuf = bufsize * 2;
atomic_set(&conn->bytes_to_rcv, 0);
conn->rmbe_update_limit =
smc_rmb_wnd_update_limit(buf_desc->len);
@@ -2386,7 +2385,7 @@ static int __smc_buf_create(struct smc_sock *smc, bool is_smcd, bool is_rmb)
smc_ism_set_conn(conn); /* map RMB/smcd_dev to conn */
} else {
conn->sndbuf_desc = buf_desc;
- smc->sk.sk_sndbuf = bufsize;
+ smc->sk.sk_sndbuf = bufsize * 2;
atomic_set(&conn->sndbuf_space, bufsize);
}
return 0;
diff --git a/net/smc/smc_sysctl.c b/net/smc/smc_sysctl.c
index b6f79fabb9d3..0b2a957ca5f5 100644
--- a/net/smc/smc_sysctl.c
+++ b/net/smc/smc_sysctl.c
@@ -21,6 +21,10 @@
static int min_sndbuf = SMC_BUF_MIN_SIZE;
static int min_rcvbuf = SMC_BUF_MIN_SIZE;
+static int max_sndbuf = INT_MAX / 2;
+static int max_rcvbuf = INT_MAX / 2;
+static const int net_smc_wmem_init = (64 * 1024);
+static const int net_smc_rmem_init = (64 * 1024);
static struct ctl_table smc_table[] = {
{
@@ -53,6 +57,7 @@ static struct ctl_table smc_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = &min_sndbuf,
+ .extra2 = &max_sndbuf,
},
{
.procname = "rmem",
@@ -61,6 +66,7 @@ static struct ctl_table smc_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = &min_rcvbuf,
+ .extra2 = &max_rcvbuf,
},
{ }
};
@@ -88,8 +94,8 @@ int __net_init smc_sysctl_net_init(struct net *net)
net->smc.sysctl_autocorking_size = SMC_AUTOCORKING_DEFAULT_SIZE;
net->smc.sysctl_smcr_buf_type = SMCR_PHYS_CONT_BUFS;
net->smc.sysctl_smcr_testlink_time = SMC_LLC_TESTLINK_DEFAULT_TIME;
- WRITE_ONCE(net->smc.sysctl_wmem, READ_ONCE(net->ipv4.sysctl_tcp_wmem[1]));
- WRITE_ONCE(net->smc.sysctl_rmem, READ_ONCE(net->ipv4.sysctl_tcp_rmem[1]));
+ WRITE_ONCE(net->smc.sysctl_wmem, net_smc_wmem_init);
+ WRITE_ONCE(net->smc.sysctl_rmem, net_smc_rmem_init);
return 0;
--
2.41.0
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH net v3 2/2] net/smc: Use correct buffer sizes when switching between TCP and SMC
2023-08-04 17:06 [PATCH net v3 0/2] net/smc: Fix effective buffer size Gerd Bayer
2023-08-04 17:06 ` [PATCH net v3 1/2] net/smc: Fix setsockopt and sysctl to specify same buffer size again Gerd Bayer
@ 2023-08-04 17:06 ` Gerd Bayer
2023-08-09 10:30 ` [PATCH net v3 0/2] net/smc: Fix effective buffer size patchwork-bot+netdevbpf
2 siblings, 0 replies; 4+ messages in thread
From: Gerd Bayer @ 2023-08-04 17:06 UTC (permalink / raw)
To: Wenjia Zhang, Jan Karcher, Tony Lu, Paolo Abeni
Cc: Karsten Graul, D . Wythe, Wen Gu, David S . Miller, Eric Dumazet,
Jakub Kicinski, linux-s390, netdev, linux-kernel
Tuning of the effective buffer size through setsockopts was working for
SMC traffic only but not for TCP fall-back connections even before
commit 0227f058aa29 ("net/smc: Unbind r/w buffer size from clcsock and
make them tunable"). That change made it apparent that TCP fall-back
connections would use net.smc.[rw]mem as buffer size instead of
net.ipv4_tcp_[rw]mem.
Amend the code that copies attributes between the (TCP) clcsock and the
SMC socket and adjust buffer sizes appropriately:
- Copy over sk_userlocks so that both sockets agree on whether tuning
via setsockopt is active.
- When falling back to TCP use sk_sndbuf or sk_rcvbuf as specified with
setsockopt. Otherwise, use the sysctl value for TCP/IPv4.
- Likewise, use either values from setsockopt or from sysctl for SMC
(duplicated) on successful SMC connect.
In smc_tcp_listen_work() drop the explicit copy of buffer sizes as that
is taken care of by the attribute copy.
Fixes: 0227f058aa29 ("net/smc: Unbind r/w buffer size from clcsock and make them tunable")
Reviewed-by: Wenjia Zhang <wenjia@linux.ibm.com>
Reviewed-by: Tony Lu <tonylu@linux.alibaba.com>
Signed-off-by: Gerd Bayer <gbayer@linux.ibm.com>
---
net/smc/af_smc.c | 73 +++++++++++++++++++++++++++++++++---------------
1 file changed, 51 insertions(+), 22 deletions(-)
diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index 5b878e523abf..f5834af5fad5 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -436,13 +436,60 @@ static int smc_bind(struct socket *sock, struct sockaddr *uaddr,
return rc;
}
+/* copy only relevant settings and flags of SOL_SOCKET level from smc to
+ * clc socket (since smc is not called for these options from net/core)
+ */
+
+#define SK_FLAGS_SMC_TO_CLC ((1UL << SOCK_URGINLINE) | \
+ (1UL << SOCK_KEEPOPEN) | \
+ (1UL << SOCK_LINGER) | \
+ (1UL << SOCK_BROADCAST) | \
+ (1UL << SOCK_TIMESTAMP) | \
+ (1UL << SOCK_DBG) | \
+ (1UL << SOCK_RCVTSTAMP) | \
+ (1UL << SOCK_RCVTSTAMPNS) | \
+ (1UL << SOCK_LOCALROUTE) | \
+ (1UL << SOCK_TIMESTAMPING_RX_SOFTWARE) | \
+ (1UL << SOCK_RXQ_OVFL) | \
+ (1UL << SOCK_WIFI_STATUS) | \
+ (1UL << SOCK_NOFCS) | \
+ (1UL << SOCK_FILTER_LOCKED) | \
+ (1UL << SOCK_TSTAMP_NEW))
+
+/* if set, use value set by setsockopt() - else use IPv4 or SMC sysctl value */
+static void smc_adjust_sock_bufsizes(struct sock *nsk, struct sock *osk,
+ unsigned long mask)
+{
+ struct net *nnet = sock_net(nsk);
+
+ nsk->sk_userlocks = osk->sk_userlocks;
+ if (osk->sk_userlocks & SOCK_SNDBUF_LOCK) {
+ nsk->sk_sndbuf = osk->sk_sndbuf;
+ } else {
+ if (mask == SK_FLAGS_SMC_TO_CLC)
+ WRITE_ONCE(nsk->sk_sndbuf,
+ READ_ONCE(nnet->ipv4.sysctl_tcp_wmem[1]));
+ else
+ WRITE_ONCE(nsk->sk_sndbuf,
+ 2 * READ_ONCE(nnet->smc.sysctl_wmem));
+ }
+ if (osk->sk_userlocks & SOCK_RCVBUF_LOCK) {
+ nsk->sk_rcvbuf = osk->sk_rcvbuf;
+ } else {
+ if (mask == SK_FLAGS_SMC_TO_CLC)
+ WRITE_ONCE(nsk->sk_rcvbuf,
+ READ_ONCE(nnet->ipv4.sysctl_tcp_rmem[1]));
+ else
+ WRITE_ONCE(nsk->sk_rcvbuf,
+ 2 * READ_ONCE(nnet->smc.sysctl_rmem));
+ }
+}
+
static void smc_copy_sock_settings(struct sock *nsk, struct sock *osk,
unsigned long mask)
{
/* options we don't get control via setsockopt for */
nsk->sk_type = osk->sk_type;
- nsk->sk_sndbuf = osk->sk_sndbuf;
- nsk->sk_rcvbuf = osk->sk_rcvbuf;
nsk->sk_sndtimeo = osk->sk_sndtimeo;
nsk->sk_rcvtimeo = osk->sk_rcvtimeo;
nsk->sk_mark = READ_ONCE(osk->sk_mark);
@@ -453,26 +500,10 @@ static void smc_copy_sock_settings(struct sock *nsk, struct sock *osk,
nsk->sk_flags &= ~mask;
nsk->sk_flags |= osk->sk_flags & mask;
+
+ smc_adjust_sock_bufsizes(nsk, osk, mask);
}
-#define SK_FLAGS_SMC_TO_CLC ((1UL << SOCK_URGINLINE) | \
- (1UL << SOCK_KEEPOPEN) | \
- (1UL << SOCK_LINGER) | \
- (1UL << SOCK_BROADCAST) | \
- (1UL << SOCK_TIMESTAMP) | \
- (1UL << SOCK_DBG) | \
- (1UL << SOCK_RCVTSTAMP) | \
- (1UL << SOCK_RCVTSTAMPNS) | \
- (1UL << SOCK_LOCALROUTE) | \
- (1UL << SOCK_TIMESTAMPING_RX_SOFTWARE) | \
- (1UL << SOCK_RXQ_OVFL) | \
- (1UL << SOCK_WIFI_STATUS) | \
- (1UL << SOCK_NOFCS) | \
- (1UL << SOCK_FILTER_LOCKED) | \
- (1UL << SOCK_TSTAMP_NEW))
-/* copy only relevant settings and flags of SOL_SOCKET level from smc to
- * clc socket (since smc is not called for these options from net/core)
- */
static void smc_copy_sock_settings_to_clc(struct smc_sock *smc)
{
smc_copy_sock_settings(smc->clcsock->sk, &smc->sk, SK_FLAGS_SMC_TO_CLC);
@@ -2479,8 +2510,6 @@ static void smc_tcp_listen_work(struct work_struct *work)
sock_hold(lsk); /* sock_put in smc_listen_work */
INIT_WORK(&new_smc->smc_listen_work, smc_listen_work);
smc_copy_sock_settings_to_smc(new_smc);
- new_smc->sk.sk_sndbuf = lsmc->sk.sk_sndbuf;
- new_smc->sk.sk_rcvbuf = lsmc->sk.sk_rcvbuf;
sock_hold(&new_smc->sk); /* sock_put in passive closing */
if (!queue_work(smc_hs_wq, &new_smc->smc_listen_work))
sock_put(&new_smc->sk);
--
2.41.0
^ permalink raw reply related [flat|nested] 4+ messages in thread