I don't think anyone can measure latency to 1% accuracy. It's
better to not even pretend to be able to. 10% should be fine
even for the most latency-critical environments.
Signed-off-by: Martin Wilck
---
libmultipath/prioritizers/path_latency.c | 5 +++--
1 file changed, 3 insertions(+), 2 delet
The warnings at here are pointless. We are looking at a single
path only. Firstly, the standdard deviation for this measurement
can't be "too low" - the lower, the more precise the measurement,
the better. Secondly, a high standard deviation indicates an
unstable path with highly variable latency.
The log standard deviation can be calculated much more simply
by realizing
sum_n (x_i - avg(x))^2 == sum_n x_i^2 - n * avg(x)^2
Also, use timespecsub rather than the custom timeval_to_usec,
and avoid taking log(0).
Signed-off-by: Martin Wilck
---
libmultipath/prioritizers/path_latency.c | 7
Hi Christophe and Guan,
I was hoping to get down to the review before Christophe committed
your your patch "calculate standard deviation on a logarithmic scale for
prioritizer path_latency". I failed to do this in timely manner, sorry.
But I still have some issues with the patch. Please check the
This is not a critical error. It just means that the path in
question will have low priority (rightly so, if it has >100s latency).
Signed-off-by: Martin Wilck
---
libmultipath/prioritizers/path_latency.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/libmultipath/prioritize
Add IBM 3542 and 3552, arrays: FAStT200 and FAStT500.
Add full STK OPENstorage family, arrays: 9176, D173, D178, D210, D220, D240 and
D280.
Add STK BladeCtlr family, arrays: B210, B220, B240 and B280.
These changes were done in multipath-tools time ago.
Cc: NetApp RDAC team
Cc: Hannes Reinecke
On Nov 15, 2017, at 7:18 PM, Qu Wenruo wrote:
>
> [Background]
> Recently I'm considering the possibility to use checksum from filesystem
> to enhance device-mapper raid.
>
> The idea behind it is quite simple, since most modern filesystems have
> checksum for their metadata, and even some (btrf
Cc: Gris Ge
Cc: Christophe Varoqui
Cc: device-mapper development
Signed-off-by: Xose Vazquez Perez
---
libdmmp/docs/kernel-doc | 164 ++--
1 file changed, 118 insertions(+), 46 deletions(-)
diff --git a/libdmmp/docs/kernel-doc b/libdmmp/docs/kernel-
