[PATCH] blktrace: Add option for setting sub buffer size

Use -b to give sub buffer size in KiB, -n to give number of
sub buffers wanted. This affects the relayfs trace setup.

diff --git a/README b/README
index 15ab22b785c3bbceafb9bffb4fe75d951b6e6691..058306fbd40ba65e4589f71e50e71d19dd29c8ee 100644 (file)
--- a/README
+++ b/README
@@ -53,6 +53,8 @@ $ blktrace -d <dev> [ -r relay_path ] [ -o output ] [ -k ] [ -w time ]
        -A Give the trace mask directly as a number.
 
        -v Print program version info.
+       -b Sub buffer size in KiB.
+       -n Number of sub buffers.
 
 $ blkparse -i <input> [ -o <output> ] [ -b rb_batch ] [ -s ] [ -t ] [ -q ]
                      [ -w start:stop ] [ -f output format ] [ -F format spec ]

diff --git a/blktrace.c b/blktrace.c
index 891b0a361c59f51813f9dd47ebc976847ff86243..69d85c568420ab1b3f7364f3ac5760f30d3e436d 100644 (file)
--- a/blktrace.c
+++ b/blktrace.c
@@ -71,7 +71,7 @@ struct mask_map mask_maps[] = {
        DECLARE_MASK_MAP(PC),
 };
 
-#define S_OPTS "d:a:A:r:o:kw:v"
+#define S_OPTS "d:a:A:r:o:kw:vb:n:"
 static struct option l_opts[] = {
        {
                .name = "dev",
@@ -121,6 +121,18 @@ static struct option l_opts[] = {
                .flag = NULL,
                .val = 'v'
        },
+       {
+               .name = "buffer size",
+               .has_arg = required_argument,
+               .flag = NULL,
+               .val = 'b'
+       },
+       {
+               .name = "nr of sub buffers",
+               .has_arg = required_argument,
+               .flag = NULL,
+               .val = 'n'
+       },
 };
 
 struct thread_information {
@@ -160,6 +172,8 @@ static char *output_name;
 static int act_mask = ~0U;
 static int kill_running_trace;
 static int use_mmap;
+static int buf_size = BUF_SIZE;
+static int buf_nr = BUF_NR;
 
 #define is_done()      (*(volatile int *)(&done))
 static volatile int done;
@@ -184,8 +198,8 @@ static int start_trace(struct device_information *dip)
        struct blk_user_trace_setup buts;
 
        memset(&buts, 0, sizeof(buts));
-       buts.buf_size = BUF_SIZE;
-       buts.buf_nr = BUF_NR;
+       buts.buf_size = buf_size;
+       buts.buf_nr = buf_nr;
        buts.act_mask = act_mask;
 
        if (ioctl(dip->fd, BLKSTARTTRACE, &buts) < 0) {
@@ -250,12 +264,12 @@ static int get_data_read(struct thread_information *tip, void *buf, int len)
 static int get_data_mmap(struct thread_information *tip, void *buf, int len,
                         int check_magic)
 {
-       if (len > (BUF_SIZE * (tip->buf_subbuf + 1)) - tip->buf_offset) {
+       if (len > (buf_size * (tip->buf_subbuf + 1)) - tip->buf_offset) {
                tip->buf_subbuf++;
-               if (tip->buf_subbuf == BUF_NR)
+               if (tip->buf_subbuf == buf_nr)
                        tip->buf_subbuf = 0;
 
-               tip->buf_offset = tip->buf_subbuf * BUF_SIZE;
+               tip->buf_offset = tip->buf_subbuf * buf_size;
        }
 
        while (1) {
@@ -343,7 +357,7 @@ static void *extract(void *arg)
        }
 
        if (use_mmap) {
-               tip->buf = mmap(NULL, BUF_SIZE * BUF_NR, PROT_READ,
+               tip->buf = mmap(NULL, buf_size * buf_nr, PROT_READ,
                                        MAP_PRIVATE | MAP_POPULATE, tip->fd, 0);
                if (tip->buf == MAP_FAILED) {
                        perror("mmap");
@@ -442,7 +456,7 @@ static int start_threads(struct device_information *dip)
 static void close_thread(struct thread_information *tip)
 {
        if (tip->buf)
-               munmap(tip->buf, BUF_SIZE * BUF_NR);
+               munmap(tip->buf, buf_size * buf_nr);
 
        if (tip->fd != -1)
                close(tip->fd);
@@ -598,6 +612,8 @@ static char usage_str[] = \
        "\t-w Stop after defined time, in seconds\n" \
        "\t-a Only trace specified actions. See documentation\n" \
        "\t-A Give trace mask as a single value. See documentation\n" \
+       "\t-b Sub buffer size in KiB\n" \
+       "\t-n Number of sub buffers\n" \
        "\t-v Print program version info\n\n";
 
 static void show_usage(char *program)
@@ -667,6 +683,23 @@ int main(int argc, char *argv[])
                case 'v':
                        printf("%s version %s\n", argv[0], blktrace_version);
                        return 0;
+               case 'b':
+                       buf_size = atoi(optarg);
+                       if (buf_size <= 0) {
+                               fprintf(stderr,
+                                       "Invalid buffer size (%d)\n", buf_size);
+                               return 1;
+                       }
+                       buf_size <<= 10;
+                       break;
+               case 'n':
+                       buf_nr = atoi(optarg);
+                       if (buf_nr <= 0) {
+                               fprintf(stderr,
+                                       "Invalid buffer nr (%d)\n", buf_nr);
+                               return 1;
+                       }
+                       break;
                default:
                        show_usage(argv[0]);
                        return 1;