2018-03-30 19:34:47

by Souvik Banerjee

Subject: [PATCH] blktrace: fix comment in blktrace_api.h

The `__u64 time` field of the blk_io_trace struct refers to
the time in nanoseconds, not in microseconds. It is set in
__blk_add_trace, which does the following:

t->time = ktime_to_ns(ktime_get());

ktime_to_ns returns ktime_t in nanoseconds, not microseconds.

Signed-off-by: Souvik Banerjee <[email protected]>
---
include/uapi/linux/blktrace_api.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/uapi/linux/blktrace_api.h b/include/uapi/linux/blktrace_api.h
index 3c50e07ee833..690621b610e5 100644
--- a/include/uapi/linux/blktrace_api.h
+++ b/include/uapi/linux/blktrace_api.h
@@ -101,7 +101,7 @@ enum blktrace_notify {
struct blk_io_trace {
__u32 magic; /* MAGIC << 8 | version */
__u32 sequence; /* event number */
- __u64 time; /* in microseconds */
+ __u64 time; /* in nanoseconds */
__u64 sector; /* disk offset */
__u32 bytes; /* transfer length */
__u32 action; /* what happened */
--
2.16.3

2018-03-30 20:18:45

by Jens Axboe

Subject: Re: [PATCH] blktrace: fix comment in blktrace_api.h

On 3/30/18 1:32 PM, Souvik Banerjee wrote:
> The `__u64 time` field of the blk_io_trace struct refers to
> the time in nanoseconds, not in microseconds. It is set in
> __blk_add_trace, which does the following:
>
> t->time = ktime_to_ns(ktime_get());
>
> ktime_to_ns returns ktime_t in nanoseconds, not microseconds.

Thanks, applied. Back way back when it used to be in microseconds, iirc,
I'm guessing the comment dates to back then.

--
Jens Axboe