[PATCH] Allow trace data to stay CPU endianness

Basically just check whether we need to convert the trace or not
in blkparse, then we can get rid of the endianness conversion
in the hot path (blktrace:write_tip_events()).

diff --git a/blkparse.c b/blkparse.c
index 7da67a609a7891e3118db33e0ae91509e8954b54..52078c49172badf2b902547140f925a74f4bdc29 100644 (file)
--- a/blkparse.c
+++ b/blkparse.c
@@ -245,6 +245,7 @@ static int ppi_hash_by_pid = 1;
 static int verbose;
 static unsigned int act_mask = -1U;
 static int stats_printed;
+static int data_is_native = -1;
 
 static unsigned int t_alloc_cache;
 static unsigned int bit_alloc_cache;
@@ -1773,6 +1774,22 @@ static int read_data(int fd, void *buffer, int bytes, int block, int *fdblock)
        return 0;
 }
 
+static inline __u16 get_pdulen(struct blk_io_trace *bit)
+{
+       if (data_is_native)
+               return bit->pdu_len;
+
+       return __bswap_16(bit->pdu_len);
+}
+
+static inline __u32 get_magic(struct blk_io_trace *bit)
+{
+       if (data_is_native)
+               return bit->magic;
+
+       return __bswap_32(bit->magic);
+}
+
 static int read_events(int fd, int always_block, int *fdblock)
 {
        struct per_dev_info *pdi = NULL;
@@ -1796,13 +1813,20 @@ static int read_events(int fd, int always_block, int *fdblock)
                        break;
                }
 
-               magic = be32_to_cpu(bit->magic);
+               /*
+                * look at first trace to check whether we need to convert
+                * data in the future
+                */
+               if (data_is_native == -1 && check_data_endianness(bit))
+                       break;
+
+               magic = get_magic(bit);
                if ((magic & 0xffffff00) != BLK_IO_TRACE_MAGIC) {
                        fprintf(stderr, "Bad magic %x\n", magic);
                        break;
                }
 
-               pdu_len = be16_to_cpu(bit->pdu_len);
+               pdu_len = get_pdulen(bit);
                if (pdu_len) {
                        void *ptr = realloc(bit, sizeof(*bit) + pdu_len);
 

diff --git a/blkrawverify.c b/blkrawverify.c
index 190f7ee4c7fb16ba21005dc83b32c6274b28e573..6cc9b29b47edd45d32cc58f7010ee68b015fddef 100644 (file)
--- a/blkrawverify.c
+++ b/blkrawverify.c
@@ -33,6 +33,8 @@ struct trace_info {
        char *string;
 };
 
+static int data_is_native = -1;
+
 #define TRACE_TO_STRING(f)     {.bit_field = f, .string = #f}
 static struct trace_info traces[] = {
        TRACE_TO_STRING( BLK_TC_READ ),

diff --git a/blktrace.c b/blktrace.c
index 0054b877d88050741736724383333354763e7ddf..a7804813ba75652216584df2643e714bebf73444 100644 (file)
--- a/blktrace.c
+++ b/blktrace.c
@@ -494,8 +494,6 @@ static int flush_subbuf(struct thread_information *tip, struct tip_subbuf *ts)
                if (offset + sizeof(*t) + pdu_len > ts->len)
                        break;
 
-               trace_to_be(t);
-
                offset += sizeof(*t) + pdu_len;
                tip->events_processed++;
                events++;

diff --git a/blktrace.h b/blktrace.h
index af5ab66e11c3d5a25f3ea88c5989f2d644f8478e..13d6e03ac8b7fc93105c424d3a369fa47911817b 100644 (file)
--- a/blktrace.h
+++ b/blktrace.h
@@ -53,6 +53,7 @@ struct per_cpu_info {
 };
 
 extern FILE *ofp;
+extern int data_is_native;
 
 #define CHECK_MAGIC(t)         (((t)->magic & 0xffffff00) == BLK_IO_TRACE_MAGIC)
 #define SUPPORTED_VERSION      (0x06)
@@ -90,24 +91,11 @@ static inline int verify_trace(struct blk_io_trace *t)
        return 0;
 }
 
-static inline void trace_to_be(struct blk_io_trace *t)
-{
-       t->magic        = cpu_to_be32(t->magic);
-       t->sequence     = cpu_to_be32(t->sequence);
-       t->time         = cpu_to_be64(t->time);
-       t->sector       = cpu_to_be64(t->sector);
-       t->bytes        = cpu_to_be32(t->bytes);
-       t->action       = cpu_to_be32(t->action);
-       t->pid          = cpu_to_be32(t->pid);
-       t->cpu          = cpu_to_be32(t->cpu);
-       t->error        = cpu_to_be16(t->error);
-       t->pdu_len      = cpu_to_be16(t->pdu_len);
-       t->device       = cpu_to_be32(t->device);
-       /* t->comm is a string (endian neutral) */
-}
-
 static inline void trace_to_cpu(struct blk_io_trace *t)
 {
+       if (data_is_native)
+               return;
+
        t->magic        = be32_to_cpu(t->magic);
        t->sequence     = be32_to_cpu(t->sequence);
        t->time         = be64_to_cpu(t->time);
@@ -122,6 +110,29 @@ static inline void trace_to_cpu(struct blk_io_trace *t)
        /* t->comm is a string (endian neutral) */
 }
 
+/*
+ * check whether data is native or not
+ */
+static inline int check_data_endianness(struct blk_io_trace *bit)
+{
+       u32 magic;
+
+       if ((bit->magic & 0xffffff00) == BLK_IO_TRACE_MAGIC) {
+               fprintf(stderr, "data is native\n");
+               data_is_native = 1;
+               return 0;
+       }
+
+       magic = __bswap_32(bit->magic);
+       if ((magic & 0xffffff00) == BLK_IO_TRACE_MAGIC) {
+               fprintf(stderr, "data is not native\n");
+               data_is_native = 0;
+               return 0;
+       }
+
+       return 1;
+}
+
 extern void set_all_format_specs(char *);
 extern int add_format_spec(char *);
 extern void process_fmt(char *, struct per_cpu_info *, struct blk_io_trace *,