net/ceph/messenger: micro-optimizations for out_msg

[PATCH 1/3] net/ceph/messenger: ceph_con_get_out_msg() returns the message pointer

Posted by Max Kellermann 1 month, 4 weeks ago

The caller in messenger_v1.c loads it anyway, so let's keep the
pointer in the register instead of reloading it from memory.  This
eliminates a tiny bit of unnecessary overhead.

Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
---
 include/linux/ceph/messenger.h | 2 +-
 net/ceph/messenger.c           | 4 ++--
 net/ceph/messenger_v1.c        | 3 +--
 3 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/include/linux/ceph/messenger.h b/include/linux/ceph/messenger.h
index 1717cc57cdac..57fa70c6edfb 100644
--- a/include/linux/ceph/messenger.h
+++ b/include/linux/ceph/messenger.h
@@ -548,7 +548,7 @@ void ceph_addr_set_port(struct ceph_entity_addr *addr, int p);
 void ceph_con_process_message(struct ceph_connection *con);
 int ceph_con_in_msg_alloc(struct ceph_connection *con,
 			  struct ceph_msg_header *hdr, int *skip);
-void ceph_con_get_out_msg(struct ceph_connection *con);
+struct ceph_msg *ceph_con_get_out_msg(struct ceph_connection *con);
 
 /* messenger_v1.c */
 int ceph_con_v1_try_read(struct ceph_connection *con);
diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index d1b5705dc0c6..7ab2176b977e 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -2109,7 +2109,7 @@ int ceph_con_in_msg_alloc(struct ceph_connection *con,
 	return ret;
 }
 
-void ceph_con_get_out_msg(struct ceph_connection *con)
+struct ceph_msg *ceph_con_get_out_msg(struct ceph_connection *con)
 {
 	struct ceph_msg *msg;
 
@@ -2140,7 +2140,7 @@ void ceph_con_get_out_msg(struct ceph_connection *con)
 	 * message or in case of a fault.
 	 */
 	WARN_ON(con->out_msg);
-	con->out_msg = ceph_msg_get(msg);
+	return con->out_msg = ceph_msg_get(msg);
 }
 
 /*
diff --git a/net/ceph/messenger_v1.c b/net/ceph/messenger_v1.c
index 0cb61c76b9b8..eebe4e19d75a 100644
--- a/net/ceph/messenger_v1.c
+++ b/net/ceph/messenger_v1.c
@@ -210,8 +210,7 @@ static void prepare_write_message(struct ceph_connection *con)
 			&con->v1.out_temp_ack);
 	}
 
-	ceph_con_get_out_msg(con);
-	m = con->out_msg;
+	m = ceph_con_get_out_msg(con);
 
 	dout("prepare_write_message %p seq %lld type %d len %d+%d+%zd\n",
 	     m, con->out_seq, le16_to_cpu(m->hdr.type),
-- 
2.47.2

Re: [PATCH 1/3] net/ceph/messenger: ceph_con_get_out_msg() returns the message pointer

Posted by Viacheslav Dubeyko 1 month, 3 weeks ago

On Wed, 2025-08-06 at 11:48 +0200, Max Kellermann wrote:
> The caller in messenger_v1.c loads it anyway, so let's keep the
> pointer in the register instead of reloading it from memory.  This
> eliminates a tiny bit of unnecessary overhead.
> 
> Signed-off-by: Max Kellermann <max.kellermann@ionos.com>

Looks good.

Reviewed-by: Viacheslav Dubeyko <Slava.Dubeyko@ibm.com>

Thanks,
Slava.

> ---
>  include/linux/ceph/messenger.h | 2 +-
>  net/ceph/messenger.c           | 4 ++--
>  net/ceph/messenger_v1.c        | 3 +--
>  3 files changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/include/linux/ceph/messenger.h b/include/linux/ceph/messenger.h
> index 1717cc57cdac..57fa70c6edfb 100644
> --- a/include/linux/ceph/messenger.h
> +++ b/include/linux/ceph/messenger.h
> @@ -548,7 +548,7 @@ void ceph_addr_set_port(struct ceph_entity_addr *addr, int p);
>  void ceph_con_process_message(struct ceph_connection *con);
>  int ceph_con_in_msg_alloc(struct ceph_connection *con,
>  			  struct ceph_msg_header *hdr, int *skip);
> -void ceph_con_get_out_msg(struct ceph_connection *con);
> +struct ceph_msg *ceph_con_get_out_msg(struct ceph_connection *con);
>  
>  /* messenger_v1.c */
>  int ceph_con_v1_try_read(struct ceph_connection *con);
> diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
> index d1b5705dc0c6..7ab2176b977e 100644
> --- a/net/ceph/messenger.c
> +++ b/net/ceph/messenger.c
> @@ -2109,7 +2109,7 @@ int ceph_con_in_msg_alloc(struct ceph_connection *con,
>  	return ret;
>  }
>  
> -void ceph_con_get_out_msg(struct ceph_connection *con)
> +struct ceph_msg *ceph_con_get_out_msg(struct ceph_connection *con)
>  {
>  	struct ceph_msg *msg;
>  
> @@ -2140,7 +2140,7 @@ void ceph_con_get_out_msg(struct ceph_connection *con)
>  	 * message or in case of a fault.
>  	 */
>  	WARN_ON(con->out_msg);
> -	con->out_msg = ceph_msg_get(msg);
> +	return con->out_msg = ceph_msg_get(msg);
>  }
>  
>  /*
> diff --git a/net/ceph/messenger_v1.c b/net/ceph/messenger_v1.c
> index 0cb61c76b9b8..eebe4e19d75a 100644
> --- a/net/ceph/messenger_v1.c
> +++ b/net/ceph/messenger_v1.c
> @@ -210,8 +210,7 @@ static void prepare_write_message(struct ceph_connection *con)
>  			&con->v1.out_temp_ack);
>  	}
>  
> -	ceph_con_get_out_msg(con);
> -	m = con->out_msg;
> +	m = ceph_con_get_out_msg(con);
>  
>  	dout("prepare_write_message %p seq %lld type %d len %d+%d+%zd\n",
>  	     m, con->out_seq, le16_to_cpu(m->hdr.type),

-- 
Viacheslav Dubeyko <Slava.Dubeyko@ibm.com>

RE: [PATCH 1/3] net/ceph/messenger: ceph_con_get_out_msg() returns the message pointer

Posted by Viacheslav Dubeyko 1 month, 3 weeks ago

On Fri, 2025-08-08 at 17:40 +0000, Viacheslav Dubeyko wrote:
> On Wed, 2025-08-06 at 11:48 +0200, Max Kellermann wrote:
> > The caller in messenger_v1.c loads it anyway, so let's keep the
> > pointer in the register instead of reloading it from memory.  This
> > eliminates a tiny bit of unnecessary overhead.
> > 
> > Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
> 
> Looks good.
> 
> Reviewed-by: Viacheslav Dubeyko <Slava.Dubeyko@ibm.com>
> 
> 

Tested-by: Viacheslav Dubeyko <Slava.Dubeyko@ibm.com>

Thanks,
Slava.