* [PATCH] block: iolatency: avoid 64-bit division
@ 2018-07-10 15:21 Arnd Bergmann
2018-07-10 18:28 ` Jens Axboe
0 siblings, 1 reply; 2+ messages in thread
From: Arnd Bergmann @ 2018-07-10 15:21 UTC (permalink / raw)
To: Jens Axboe
Cc: Arnd Bergmann, Tejun Heo, Josef Bacik, linux-block, linux-kernel
On 32-bit architectures, dividing a 64-bit number needs to use the
do_div() function or something like it to avoid a link failure:
block/blk-iolatency.o: In function `iolatency_prfill_limit':
blk-iolatency.c:(.text+0x8cc): undefined reference to `__aeabi_uldivmod'
Using div_u64() gives us the best output and avoids the need for an
explicit cast.
Fixes: d70675121546 ("block: introduce blk-iolatency io controller")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
block/blk-iolatency.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c
index a35a1f580337..56ddb2c68752 100644
--- a/block/blk-iolatency.c
+++ b/block/blk-iolatency.c
@@ -798,8 +798,7 @@ static u64 iolatency_prfill_limit(struct seq_file *sf,
if (!dname || !iolat->min_lat_nsec)
return 0;
seq_printf(sf, "%s target=%llu\n",
- dname,
- (unsigned long long)iolat->min_lat_nsec / NSEC_PER_USEC);
+ dname, div_u64(iolat->min_lat_nsec, NSEC_PER_USEC));
return 0;
}
--
2.9.0
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] block: iolatency: avoid 64-bit division
2018-07-10 15:21 [PATCH] block: iolatency: avoid 64-bit division Arnd Bergmann
@ 2018-07-10 18:28 ` Jens Axboe
0 siblings, 0 replies; 2+ messages in thread
From: Jens Axboe @ 2018-07-10 18:28 UTC (permalink / raw)
To: Arnd Bergmann; +Cc: Tejun Heo, Josef Bacik, linux-block, linux-kernel
On 7/10/18 9:21 AM, Arnd Bergmann wrote:
> On 32-bit architectures, dividing a 64-bit number needs to use the
> do_div() function or something like it to avoid a link failure:
>
> block/blk-iolatency.o: In function `iolatency_prfill_limit':
> blk-iolatency.c:(.text+0x8cc): undefined reference to `__aeabi_uldivmod'
>
> Using div_u64() gives us the best output and avoids the need for an
> explicit cast.
Applied, thanks Arnd.
--
Jens Axboe
^ permalink raw reply [flat|nested] 2+ messages in thread
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