[Crash-utility] [PATCH] dev: improvement for displaying I/O statics for blk-mq disk
Dave Anderson
anderson at redhat.com
Wed Oct 12 15:32:57 UTC 2016
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".
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.mizuma at 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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> Crash-utility at redhat.com
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>
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