High latency in metada write


shadow_vector@...
 

Hello everyone:
  Recently, I did some testing with daos array interface, found that after finishing nvme bio, it took me a long time for writing metadata and resource release ; The total latency of single channel IO is about 80us, and  vos_update_end taks about 30 us(about 17us in dkey akey update via SCM); I thought that IO via SCM should be very fast, but through the test, it's slower than the nvme IO. Is evtree operation takes too long or are there other reasons?

Best regards!


Lombardi, Johann
 

Hi there,

 

Could you please tell us more about your HW configuration and the test case (e.g. I/O size, read or write, object class, …)? We definitely see lower latency in our internal testing.

 

Cheers,

Johann

 

From: <daos@daos.groups.io> on behalf of "shadow_vector@..." <shadow_vector@...>
Reply-To: "daos@daos.groups.io" <daos@daos.groups.io>
Date: Tuesday 11 January 2022 at 12:26
To: "daos@daos.groups.io" <daos@daos.groups.io>
Subject: [daos] High latency in metada write

 

Hello everyone:
  Recently, I did some testing with daos array interface, found that after finishing nvme bio, it took me a long time for writing metadata and resource release ; The total latency of single channel IO is about 80us, and  vos_update_end taks about 30 us(about 17us in dkey akey update via SCM); I thought that IO via SCM should be very fast, but through the test, it's slower than the nvme IO. Is evtree operation takes too long or are there other reasons?

Best regards!

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shadow_vector@...
 


Here is my HW configuration:

CPU: Intel(R) Xeon(R) Gold 6248R CPU @ 3.00GHz
SCM:2 SCM ,256GB
I use array interface in this test and set the obj class to OC_RP_3GX.  32GB for hugepage config;The IO size is 4K,only write req was sent.


Thanks for response.