[PATCH V6 09/13] scsi: put hot fields of scsi_host_template into one cacheline

Ming Lei
2021-01-18T00:52:16Z

The following three fields of scsi_host_template are referenced in
scsi IO submission path, so put them together into one cacheline:

- cmd_size
- queuecommand
- commit_rqs

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>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
include/scsi/scsi_host.h | 72 ++++++++++++++++++++++------------------
1 file changed, 39 insertions(+), 33 deletions(-)

diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 701f178b20ae..2d6e3a1f5f0b 100644
--- 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
@@ -478,10 +488,6 @@ 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 */
--
2.28.0