scsi: core: Put hot fields of scsi_host_template in one cacheline

The following three fields of scsi_host_template are referenced in the SCSI
I/O submission hot path. Put them together in one cacheline:

 - cmd_size

 - queuecommand

 - commit_rqs

Link: https://lore.kernel.org/r/20210122023317.687987-10-ming.lei@redhat.com
Cc: Omar Sandoval <osandov@fb.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Cc: Ewan D. Milne <emilne@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Tested-by: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index e30fd963b97d0c977a7e6c50f9395d46d47b7db9..f0e8a9e7300218fd82187195ebef940352c40826 100644 (file)
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -30,40 +30,15 @@ struct scsi_transport_template;
 #define MODE_TARGET 0x02
 
 struct scsi_host_template {
-       struct module *module;
-       const char *name;
-
        /*
-        * The info function will return whatever useful information the
-        * developer sees fit.  If not provided, then the name field will
-        * be used instead.
-        *
-        * Status: OPTIONAL
+        * Put fields referenced in IO submission path together in
+        * same cacheline
         */
-       const char *(* info)(struct Scsi_Host *);
 
        /*
-        * Ioctl interface
-        *
-        * Status: OPTIONAL
-        */
-       int (*ioctl)(struct scsi_device *dev, unsigned int cmd,
-                    void __user *arg);
-
-
-#ifdef CONFIG_COMPAT
-       /* 
-        * Compat handler. Handle 32bit ABI.
-        * When unknown ioctl is passed return -ENOIOCTLCMD.
-        *
-        * Status: OPTIONAL
+        * Additional per-command data allocated for the driver.
         */
-       int (*compat_ioctl)(struct scsi_device *dev, unsigned int cmd,
-                           void __user *arg);
-#endif
-
-       int (*init_cmd_priv)(struct Scsi_Host *shost, struct scsi_cmnd *cmd);
-       int (*exit_cmd_priv)(struct Scsi_Host *shost, struct scsi_cmnd *cmd);
+       unsigned int cmd_size;
 
        /*
         * The queuecommand function is used to queue up a scsi
@@ -111,6 +86,41 @@ struct scsi_host_template {
         */
        void (*commit_rqs)(struct Scsi_Host *, u16);
 
+       struct module *module;
+       const char *name;
+
+       /*
+        * The info function will return whatever useful information the
+        * developer sees fit.  If not provided, then the name field will
+        * be used instead.
+        *
+        * Status: OPTIONAL
+        */
+       const char *(*info)(struct Scsi_Host *);
+
+       /*
+        * Ioctl interface
+        *
+        * Status: OPTIONAL
+        */
+       int (*ioctl)(struct scsi_device *dev, unsigned int cmd,
+                    void __user *arg);
+
+
+#ifdef CONFIG_COMPAT
+       /*
+        * Compat handler. Handle 32bit ABI.
+        * When unknown ioctl is passed return -ENOIOCTLCMD.
+        *
+        * Status: OPTIONAL
+        */
+       int (*compat_ioctl)(struct scsi_device *dev, unsigned int cmd,
+                           void __user *arg);
+#endif
+
+       int (*init_cmd_priv)(struct Scsi_Host *shost, struct scsi_cmnd *cmd);
+       int (*exit_cmd_priv)(struct Scsi_Host *shost, struct scsi_cmnd *cmd);
+
        /*
         * This is an error handling strategy routine.  You don't need to
         * define one of these if you don't want to - there is a default
@@ -484,10 +494,6 @@ struct scsi_host_template {
         */
        u64 vendor_id;
 
-       /*
-        * Additional per-command data allocated for the driver.
-        */
-       unsigned int cmd_size;
        struct scsi_host_cmd_pool *cmd_pool;
 
        /* Delay for runtime autosuspend */