[PATCH 0/2] stat/options patches

[PATCH 0/2] stat/options patches

[vincentfu]

From: Vincent Fu <vincent.fu@wdc.com>

Jens, please consider these two patches that address a couple issues
that we have encountered. Thanks.

Vincent

Vincent Fu (2):
  stat: use long doubles to identify latency percentiles
  options: catch division by zero in setting CPU affinity

 options.c | 3 +++
 stat.c    | 5 ++++-
 2 files changed, 7 insertions(+), 1 deletion(-)

-- 
2.17.1

[PATCH 1/2] stat: use long doubles to identify latency percentiles

[vincentfu]

From: Vincent Fu <vincent.fu@wdc.com>

In some cases, the 100th percentile latency is not correctly identified
because of problems with double precision floating point arithmetic.
Use long doubles instead in the while loop condition to reduce the
likelihood of encountering this problem.

Also, print an error message when latency percentiles are not
successfully identified.
---
 stat.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/stat.c b/stat.c
index c1f46e1d..66a13bca 100644
--- a/stat.c
+++ b/stat.c
@@ -170,7 +170,7 @@ unsigned int calc_clat_percentiles(uint64_t *io_u_plat, unsigned long long nr,
 	is_last = false;
 	for (i = 0; i < FIO_IO_U_PLAT_NR && !is_last; i++) {
 		sum += io_u_plat[i];
-		while (sum >= (plist[j].u.f / 100.0 * nr)) {
+		while (sum >= ((long double) plist[j].u.f / 100.0 * nr)) {
 			assert(plist[j].u.f <= 100.0);
 
 			ovals[j] = plat_idx_to_val(i);
@@ -187,6 +187,9 @@ unsigned int calc_clat_percentiles(uint64_t *io_u_plat, unsigned long long nr,
 		}
 	}
 
+	if (!is_last)
+		log_err("fio: error calculating latency percentiles\n");
+
 	*output = ovals;
 	return len;
 }
-- 
2.17.1

[PATCH 2/2] options: catch division by zero in setting CPU affinity

[vincentfu]

From: Vincent Fu <vincent.fu@wdc.com>

Catch a division by zero and abort with a helpful message instead of a
signal 8 floating point error.
---
 options.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/options.c b/options.c
index 6d832354..95086074 100644
--- a/options.c
+++ b/options.c
@@ -493,6 +493,9 @@ int fio_cpus_split(os_cpu_mask_t *mask, unsigned int cpu_index)
 	const long max_cpu = cpus_online();
 
 	cpus_in_mask = fio_cpu_count(mask);
+	if (!cpus_in_mask)
+		return 0;
+
 	cpu_index = cpu_index % cpus_in_mask;
 
 	index = 0;
-- 
2.17.1

Re: [PATCH 0/2] stat/options patches

[Jens Axboe]

On 2/19/19 2:44 PM, vincentfu@gmail.com wrote:
> From: Vincent Fu <vincent.fu@wdc.com>
> 
> Jens, please consider these two patches that address a couple issues
> that we have encountered. Thanks.

Applied, thanks Vincent.

-- 
Jens Axboe