dm vdo indexer: reorder uds_request to reduce padding

Reorder fields and make uds_request_type and uds_zone_message packed,
to squeeze out some space. Use struct_group so the request reset code
no longer needs to care about field order.

On x86_64 this reduces the struct size from 144 to 120, which saves 48
kB (about 12%) per VDO hash zone.

Signed-off-by: Ken Raeburn <raeburn@redhat.com>
Signed-off-by: Matthew Sakai <msakai@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>

diff --git a/drivers/md/dm-vdo/indexer/index-session.c b/drivers/md/dm-vdo/indexer/index-session.c
index aee0914d604a5f452627eeb57d3ba1952e3a9486..aa575a24e0b2f9cba1b98d20aa8001396452df23 100644 (file)
--- a/drivers/md/dm-vdo/indexer/index-session.c
+++ b/drivers/md/dm-vdo/indexer/index-session.c
@@ -100,7 +100,6 @@ static int get_index_session(struct uds_index_session *index_session)
 
 int uds_launch_request(struct uds_request *request)
 {
-       size_t internal_size;
        int result;
 
        if (request->callback == NULL) {
@@ -121,10 +120,7 @@ int uds_launch_request(struct uds_request *request)
        }
 
        /* Reset all internal fields before processing. */
-       internal_size =
-               sizeof(struct uds_request) - offsetof(struct uds_request, zone_number);
-       // FIXME should be using struct_group for this instead
-       memset((char *) request + sizeof(*request) - internal_size, 0, internal_size);
+       memset(&request->internal, 0, sizeof(request->internal));
 
        result = get_index_session(request->session);
        if (result != UDS_SUCCESS)

diff --git a/drivers/md/dm-vdo/indexer/indexer.h b/drivers/md/dm-vdo/indexer/indexer.h
index 183a94eb7e923f3e6a1cde1aeffc8b832baecb7a..7c1fc4577f5bcfc7c0e5ecb7e872b0c10b66fa23 100644 (file)
--- a/drivers/md/dm-vdo/indexer/indexer.h
+++ b/drivers/md/dm-vdo/indexer/indexer.h
@@ -8,6 +8,7 @@
 
 #include <linux/mutex.h>
 #include <linux/sched.h>
+#include <linux/stddef.h>
 #include <linux/types.h>
 #include <linux/wait.h>
 
@@ -73,7 +74,7 @@ enum uds_request_type {
        /* Remove any mapping for a name. */
        UDS_DELETE,
 
-};
+} __packed;
 
 enum uds_open_index_type {
        /* Create a new index. */
@@ -226,7 +227,7 @@ struct uds_zone_message {
        enum uds_zone_message_type type;
        /* The virtual chapter number to which the message applies */
        u64 virtual_chapter;
-};
+} __packed;
 
 struct uds_index_session;
 struct uds_index;
@@ -253,34 +254,32 @@ struct uds_request {
 
        /* The existing data associated with the request name, if any */
        struct uds_record_data old_metadata;
-       /* Either UDS_SUCCESS or an error code for the request */
-       int status;
        /* True if the record name had an existing entry in the index */
        bool found;
+       /* Either UDS_SUCCESS or an error code for the request */
+       int status;
 
-       /*
-        * The remaining fields are used internally and should not be altered by clients. The index
-        * relies on zone_number being the first field in this section.
-        */
-
-       /* The number of the zone which will process this request*/
-       unsigned int zone_number;
-       /* A link for adding a request to a lock-free queue */
-       struct funnel_queue_entry queue_link;
-       /* A link for adding a request to a standard linked list */
-       struct uds_request *next_request;
-       /* A pointer to the index processing this request */
-       struct uds_index *index;
-       /* Control message for coordinating between zones */
-       struct uds_zone_message zone_message;
-       /* If true, process request immediately by waking the worker thread */
-       bool unbatched;
-       /* If true, continue this request before processing newer requests */
-       bool requeued;
-       /* The virtual chapter containing the record name, if known */
-       u64 virtual_chapter;
-       /* The region of the index containing the record name */
-       enum uds_index_region location;
+       /* The remaining fields are used internally and should not be altered by clients. */
+       struct_group(internal,
+                    /* The virtual chapter containing the record name, if known */
+                    u64 virtual_chapter;
+                    /* The region of the index containing the record name */
+                    enum uds_index_region location;
+                    /* If true, process request immediately by waking the worker thread */
+                    bool unbatched;
+                    /* If true, continue this request before processing newer requests */
+                    bool requeued;
+                    /* Control message for coordinating between zones */
+                    struct uds_zone_message zone_message;
+                    /* The number of the zone which will process this request*/
+                    unsigned int zone_number;
+                    /* A link for adding a request to a lock-free queue */
+                    struct funnel_queue_entry queue_link;
+                    /* A link for adding a request to a standard linked list */
+                    struct uds_request *next_request;
+                    /* A pointer to the index processing this request */
+                    struct uds_index *index;
+                    );
 };
 
 /* A session is required for most index operations. */