On Fri, Dec 24, 2021 at 3:34 PM HAGIO KAZUHITO(萩尾 一仁)
<k-hagio-ab@xxxxxxx> wrote:
>
> > -----Original Message-----
> > On Fri, Dec 24, 2021 at 1:14 PM HAGIO KAZUHITO(萩尾 一仁)
> > <k-hagio-ab@xxxxxxx> wrote:
> > >
> > > Hi Lianbo,
> > >
> > > -----Original Message-----
> > > > Kernel commit <9a14d6ce4135> ("block: remove debugfs blk_mq_ctx
> > > > dispatched/merged/completed attributes") removed the member
> > > > rq_dispatched and rq_completed from struct blk_mq_ctx. Without
> > > > this patch, crash will fail with the following error:
> > > >
> > > > crash> dev -d
> > > > MAJOR GENDISK NAME REQUEST_QUEUE TOTAL ASYNC SYNC
> > > >
> > > > dev: invalid structure member offset: blk_mq_ctx_rq_dispatched
> > > > FILE: dev.c LINE: 4229 FUNCTION: get_one_mctx_diskio()
> > >
> > > Thank you for working on this.
> > > IIUC, crash will need sbitmap functionality to support this fully.
> > >
> > > Meanwhile, I think it's OK to skip the count, but it should say "actually zero"
> > > or "not supported" so that users can know it, for example:
> > >
> > Thank you for the comment, Kazu.
> >
> > > crash> dev -d
> > > MAJOR GENDISK NAME REQUEST_QUEUE TOTAL ASYNC SYNC
> > > 8 ffff92bbd102e400 sdb ffff92bbf04e3678 0 0 0
> > > dev: sdb: Disk I/O statistics is not supported in this kernel
> > > 8 ffff92bbd1014400 sdc ffff92bbf04e26e8 0 0 0
> > > dev: sdc: Disk I/O statistics is not supported in this kernel
> > > 11 ffff92c347da5e00 sr0 ffff92bbd9c3e528 0 0 0
> > > 253 ffff92bbca726e00 dm-0 ffff92bbcad7dd60 0 0 0
> > >
> > > What do you think?
> > >
> >
> > I agree with you that it should be good to have the above information
> > for users, but it looks like the statistics result is redundant and
> > the readability is not very good. What do you think of removing that
> > statistical result and only outputting prompt information? For
> > example:
> >
> > crash> dev -d
> > MAJOR GENDISK NAME REQUEST_QUEUE TOTAL ASYNC SYNC
> > dev: sda: Disk I/O statistics is not supported in this kernel
> > dev: sr0: Disk I/O statistics is not supported in this kernel
> > dev: dm-0: Disk I/O statistics is not supported in this kernel
> > dev: dm-1: Disk I/O statistics is not supported in this kernel
> > dev: dm-2: Disk I/O statistics is not supported in this kernel
>
> I would prefer to display information like the addresses of request_queue
> as far as we can. No statistics, but still we will often want to see the
> structures.
>
> So for example:
>
> crash> dev -d
> MAJOR GENDISK NAME REQUEST_QUEUE TOTAL ASYNC SYNC
> 8 ffff92bbd102e400 sdb ffff92bbf04e3678 (not supported)
> 8 ffff92bbd1014400 sdc ffff92bbf04e26e8 0 0 0
> ...
> crash> request_queue ffff92bbf04e3678 | head -n 3
> struct request_queue {
> last_merge = 0x0,
> elevator = 0xffff92bbc449b000,
>
> Is this possible?
>
Yes, thanks for the suggestion, it looks good. Will post v2 later.
crash> dev -d
MAJOR GENDISK NAME REQUEST_QUEUE TOTAL ASYNC SYNC
8 ffff996f81fb1800 sda ffff996f82545750
(not supported)
11 ffff99722a8d1000 sr0 ffff996f82540fe0
(not supported)
253 ffff9970b4671c00 dm-0 ffff9970b6505750
(not supported)
253 ffff9970b3493200 dm-1 ffff9970b5d8e730
(not supported)
253 ffff99722a8d5c00 dm-2 ffff996f851a5750
(not supported)
> >
> > How about the following changes?
> > ---
> > dev.c | 6 ++++++
> > 1 file changed, 6 insertions(+)
> >
> > diff --git a/dev.c b/dev.c
> > index effe789f38d8..3cf70c41cd17 100644
> > --- a/dev.c
> > +++ b/dev.c
> > @@ -4465,6 +4465,12 @@ display_one_diskio(struct iter *i, unsigned
> > long gendisk, ulong flags)
> > if (is_skipped_disk(disk_name))
> > return;
> >
> > + if (!MEMBER_EXISTS("blk_mq_ctx", "rq_dispatched") &&
> > + !MEMBER_EXISTS("blk_mq_ctx", "rq_completed")) {
> > + fprintf(fp, "dev: %s: Disk I/O statistics is not
> > supported in this kernel\n", disk_name);
> > + return;
> > + }
> > +
> > readmem(gendisk + OFFSET(gendisk_queue), KVADDR, &queue_addr,
> > sizeof(ulong), "gen_disk.queue", FAULT_ON_ERROR);
> > readmem(gendisk + OFFSET(gendisk_major), KVADDR, &major, sizeof(int),
> > --
> >
> >
> > Thanks.
> > Lianbo
> >
> > >
> > > >
> > > > Signed-off-by: Lianbo Jiang <lijiang@xxxxxxxxxx>
> > > > ---
> > > > dev.c | 4 ++++
> > > > 1 file changed, 4 insertions(+)
> > > >
> > > > diff --git a/dev.c b/dev.c
> > > > index effe789f38d8..dd21511e5dfc 100644
> > > > --- a/dev.c
> > > > +++ b/dev.c
> > > > @@ -4246,6 +4246,10 @@ get_mq_diskio(unsigned long q, unsigned long *mq_count)
> > > > unsigned long mctx_addr;
> > > > struct diskio tmp;
> > > >
> > > > + if (!MEMBER_EXISTS("blk_mq_ctx", "rq_dispatched") &&
> > > > + !MEMBER_EXISTS("blk_mq_ctx", "rq_completed"))
> > > > + return;
> > > > +
> > > > memset(&tmp, 0x00, sizeof(struct diskio));
> > > >
> > > > readmem(q + OFFSET(request_queue_queue_ctx), KVADDR, &queue_ctx,
> > > > --
> > > > 2.20.1
> > >
--
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