Hi Dave,

On Wed, 12 Oct 2016 11:32:57 -0400 Dave Anderson wrote:


Hello Masayoshi,

I moved the new offset_table entries to the end of the structure to
prevent any pre-existing extension modules from breaking, and I added
their offsets to the dump_offset_table() function for "help -o".

Thank you for the additional changes!

- Masayoshi Mizuma


Queued for crash-7.1.6:

   
https://github.com/crash-utility/crash/commit/df08978f31ba39e94b3096804f4e0776373c8b53

Thanks,
   Dave


----- Original Message -----
Improvement -d option of dev command to display I/O statics
for the disk which the device driver uses blk-mq interface.

Current dev -d displays always 0 in the all fields for the
blk-mq disk because blk-mq does not increment/decrement to
request_list.count[2] on I/O creation and I/O completion.

The following value is used in blk-mq on such situation.

- I/O creation:   blk_mq_ctx.rq_dispatched[2]
- I/O completion: blk_mq_ctx.rq_completed[2]

So, we can get the counter of in progress I/Os as follows.

in progress I/Os == rq_dispatched - rq_completed

This patch displays the result of above calculation for the
disk. It judges as the device driver uses blk-mq if the
request_queue.mq_ops is not NULL.

"DRV" field is displayed as "N/A(MQ)" because the value for in-flight
in the device driver is not exists for blk-mq...

Signed-off-by: Masayoshi Mizuma <m.miz...@jp.fujitsu.com>
---
  defs.h |  4 +++
  dev.c  | 98
  ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++------
  help.c |  4 ++-
  3 files changed, 96 insertions(+), 10 deletions(-)

diff --git a/defs.h b/defs.h
index a09fa9a..55c28c5 100755
--- a/defs.h
+++ b/defs.h
@@ -1822,6 +1822,10 @@ struct offset_table {                    /* stash of
commonly-used offsets */
        long request_list_count;
        long request_queue_in_flight;
        long request_queue_rq;
+       long request_queue_mq_ops;
+       long request_queue_queue_ctx;
+       long blk_mq_ctx_rq_dispatched;
+       long blk_mq_ctx_rq_completed;
        long subsys_private_klist_devices;
        long subsystem_kset;
        long mount_mnt_parent;
diff --git a/dev.c b/dev.c
index c18f40e..e46081e 100644
--- a/dev.c
+++ b/dev.c
@@ -3800,18 +3800,84 @@ again:
        return i->get_gendisk(klist_node_address);
  }

+static int
+use_mq_interface(unsigned long q)
+{
+       unsigned long mq_ops;
+
+       if (!VALID_MEMBER(request_queue_mq_ops))
+               return 0;
+
+       readmem(q + OFFSET(request_queue_mq_ops), KVADDR, &mq_ops,
+               sizeof(ulong), "request_queue.mq_ops", FAULT_ON_ERROR);
+
+       if (mq_ops == 0)
+               return 0;
+       else
+               return 1;
+}
+
+static void
+get_one_mctx_diskio(unsigned long mctx, struct diskio *io)
+{
+       unsigned long dispatch[2];
+       unsigned long comp[2];
+
+       readmem(mctx + OFFSET(blk_mq_ctx_rq_dispatched),
+               KVADDR, dispatch, sizeof(ulong) * 2, "blk_mq_ctx.rq_dispatched",
+               FAULT_ON_ERROR);
+
+       readmem(mctx + OFFSET(blk_mq_ctx_rq_completed),
+               KVADDR, comp, sizeof(ulong) * 2, "blk_mq_ctx.rq_completed",
+               FAULT_ON_ERROR);
+
+       io->read = (dispatch[0] - comp[0]);
+       io->write = (dispatch[1] - comp[1]);
+}
+
+static void
+get_mq_diskio(unsigned long q, unsigned long *mq_count)
+{
+       int cpu;
+       unsigned long queue_ctx;
+       unsigned long mctx_addr;
+       struct diskio tmp;
+
+       memset(&tmp, 0x00, sizeof(struct diskio));
+
+       readmem(q + OFFSET(request_queue_queue_ctx), KVADDR, &queue_ctx,
+               sizeof(ulong), "request_queue.queue_ctx",
+               FAULT_ON_ERROR);
+
+       for (cpu = 0; cpu < kt->cpus; cpu++) {
+               if ((kt->flags & SMP) && (kt->flags & PER_CPU_OFF)) {
+                       mctx_addr = queue_ctx + kt->__per_cpu_offset[cpu];
+                       get_one_mctx_diskio(mctx_addr, &tmp);
+                       mq_count[0] += tmp.read;
+                       mq_count[1] += tmp.write;
+               }
+       }
+}
+
  /* read request_queue.rq.count[2] */
  static void
  get_diskio_1(unsigned long rq, struct diskio *io)
  {
        int count[2];
+       unsigned long mq_count[2] = { 0 };

-       readmem(rq + OFFSET(request_queue_rq) + OFFSET(request_list_count),
-               KVADDR, count, sizeof(int) * 2, "request_list.count",
-               FAULT_ON_ERROR);
+       if (!use_mq_interface(rq)) {
+               readmem(rq + OFFSET(request_queue_rq) +
+                       OFFSET(request_list_count), KVADDR, count,
+                       sizeof(int) * 2, "request_list.count", FAULT_ON_ERROR);

-       io->read = count[0];
-       io->write = count[1];
+               io->read = count[0];
+               io->write = count[1];
+       } else {
+               get_mq_diskio(rq, mq_count);
+               io->read = mq_count[0];
+               io->write = mq_count[1];
+       }
  }

  /* request_queue.in_flight contains total requests */
@@ -3961,9 +4027,8 @@ display_one_diskio(struct iter *i, unsigned long
gendisk)
        readmem(gendisk + OFFSET(gendisk_major), KVADDR, &major, sizeof(int),
                "gen_disk.major", FAULT_ON_ERROR);
        i->get_diskio(queue_addr, &io);
-       in_flight = i->get_in_flight(queue_addr);

-       fprintf(fp, "%s%s%s  %s%s%s%s  %s%5d%s%s%s%s%s%5u\n",
+       fprintf(fp, "%s%s%s  %s%s%s%s  %s%5d%s%s%s%s%s",
                mkstring(buf0, 5, RJUST|INT_DEC, (char *)(unsigned long)major),
                space(MINSPACE),
                mkstring(buf1, VADDR_PRLEN, LJUST|LONG_HEX, (char *)gendisk),
@@ -3980,8 +4045,13 @@ display_one_diskio(struct iter *i, unsigned long
gendisk)
                space(MINSPACE),
                mkstring(buf5, 5, RJUST|INT_DEC,
                        (char *)(unsigned long)io.write),
-               space(MINSPACE),
-               in_flight);
+               space(MINSPACE));
+
+       if (!use_mq_interface(queue_addr)) {
+               in_flight = i->get_in_flight(queue_addr);
+               fprintf(fp, "%5u\n", in_flight);
+       } else
+               fprintf(fp, "%s\n", "N/A(MQ)");
  }

  static void
@@ -4056,6 +4126,16 @@ void diskio_init(void)
                MEMBER_OFFSET_INIT(request_queue_rq, "request_queue", "rq");
        else
                MEMBER_OFFSET_INIT(request_queue_rq, "request_queue", 
"root_rl");
+       if (MEMBER_EXISTS("request_queue", "mq_ops")) {
+               MEMBER_OFFSET_INIT(request_queue_mq_ops, "request_queue",
+                       "mq_ops");
+               ANON_MEMBER_OFFSET_INIT(request_queue_queue_ctx,
+                       "request_queue", "queue_ctx");
+               MEMBER_OFFSET_INIT(blk_mq_ctx_rq_dispatched, "blk_mq_ctx",
+                       "rq_dispatched");
+               MEMBER_OFFSET_INIT(blk_mq_ctx_rq_completed, "blk_mq_ctx",
+                       "rq_completed");
+       }
        MEMBER_OFFSET_INIT(subsys_private_klist_devices, "subsys_private",
                "klist_devices");
        MEMBER_OFFSET_INIT(subsystem_kset, "subsystem", "kset");
diff --git a/help.c b/help.c
index 938251f..cfa0516 100644
--- a/help.c
+++ b/help.c
@@ -2684,7 +2684,9 @@ char *help_dev[] = {
  "         ASYNC: I/O requests that are asynchronous",
  "          READ: I/O requests that are reads (older kernels)",
  "         WRITE: I/O requests that are writes (older kernels)",
-"           DRV: I/O requests that are in-flight in the device driver",
+"           DRV: I/O requests that are in-flight in the device driver.",
+"                If the device driver uses blk-mq interface, this field",
+"                shows N/A(MQ).",
  "\nEXAMPLES",
  "  Display character and block device data:\n",
  "    %s> dev",
--
1.8.3.1

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