Comments on: New mechanism: kcollect https://www.dragonflydigest.com/2017/08/07/new-mechanism-kcollect/ A running description of activity related to DragonFly BSD. Tue, 08 Aug 2017 19:19:56 +0000 hourly 1 https://wordpress.org/?v=6.9.4 By: SolarFlame https://www.dragonflydigest.com/2017/08/07/new-mechanism-kcollect/comment-page-1/#comment-486679 Tue, 08 Aug 2017 19:19:56 +0000 https://www.dragonflydigest.com/?p=20061#comment-486679 @Jenkins

Yes people do…

http://dtrace.org/blogs/brendan/2012/08/09/10-performance-wins/

https://milek.blogspot.de/2012/10/running-openafs-on-solaris-11-x86-zfs.html

and the all-time favourite question do I need to kldload aesni to make openssl AES go faster?!

https://crc32c.blogspot.com/2017/05/freebsd-aesni4-and-openssl.html

This list could go on and on…

]]> By: Kacy https://www.dragonflydigest.com/2017/08/07/new-mechanism-kcollect/comment-page-1/#comment-486678 Tue, 08 Aug 2017 18:28:33 +0000 https://www.dragonflydigest.com/?p=20061#comment-486678 On the topic of system load, a Netflix engineer has a great blog post today on what system load even means and how to interrupt kernel system data.

http://www.brendangregg.com/blog/2017-08-08/linux-load-averages.html

]]> By: Justin Sherrill https://www.dragonflydigest.com/2017/08/07/new-mechanism-kcollect/comment-page-1/#comment-486677 Tue, 08 Aug 2017 17:26:13 +0000 https://www.dragonflydigest.com/?p=20061#comment-486677 For what it’s worth, I think DTrace and kcollect are solving two different problems. kcollect is very light and was written in an afternoon, as far as I can tell, to assist with problem diagnosis in as automatic a way as possible – autocollection, graph generation, etc. DTrace is very capable but it’s a porting effort and a different approach.

I saw this without directly interacting with either right now, so I could be wrong.

]]> By: Jenkins https://www.dragonflydigest.com/2017/08/07/new-mechanism-kcollect/comment-page-1/#comment-486676 Tue, 08 Aug 2017 16:47:23 +0000 https://www.dragonflydigest.com/?p=20061#comment-486676 Serious question. Do people find DTrace useful and a good tool?

]]> By: SolarFlame https://www.dragonflydigest.com/2017/08/07/new-mechanism-kcollect/comment-page-1/#comment-486675 Tue, 08 Aug 2017 14:28:21 +0000 https://www.dragonflydigest.com/?p=20061#comment-486675 @Pedro

DTrace probes aren’t free…

http://dtrace.org/blogs/brendan/2011/02/18/dtrace-pid-provider-overhead/

]]> By: Pedro https://www.dragonflydigest.com/2017/08/07/new-mechanism-kcollect/comment-page-1/#comment-486674 Tue, 08 Aug 2017 14:17:41 +0000 https://www.dragonflydigest.com/?p=20061#comment-486674 @SolarFlame

Dtrace is also lockless. Yes, you have to collect the data but you can do the same with much better detail and no performance impact.

]]> By: mer https://www.dragonflydigest.com/2017/08/07/new-mechanism-kcollect/comment-page-1/#comment-486673 Tue, 08 Aug 2017 14:06:50 +0000 https://www.dragonflydigest.com/?p=20061#comment-486673 sysctl’s may be already collecting data, but it sounds like kcollect is a “periodic snapshot” of some sysctls, aggregated and presented via a plottable interface. Basically, saving you the trouble of writing a userland that periodically polls a bunch of sysctls and doing the same thing. A quick glance at commit messages at least one mentioned “lockless”, which not all the sysctl interfaces are.
DTrace is good, but again, requires you to do something in userland to collect and present the data.

]]> By: SolarFlame https://www.dragonflydigest.com/2017/08/07/new-mechanism-kcollect/comment-page-1/#comment-486672 Tue, 08 Aug 2017 10:40:12 +0000 https://www.dragonflydigest.com/?p=20061#comment-486672 @Pedro

those probes only fire when you’re tracing for them, kcollect runs all the time.

I think it’s better to compare it with Solaris’ kstats. OTOH DFly is already collecting stats via sysctl’s, so why another mechanism like kcollect?

]]> By: Pedro https://www.dragonflydigest.com/2017/08/07/new-mechanism-kcollect/comment-page-1/#comment-486671 Tue, 08 Aug 2017 05:47:42 +0000 https://www.dragonflydigest.com/?p=20061#comment-486671 DTrace has specific probes and is more fine-grained: it lets you know exactly what the kernel is doing. More importantly, it carries its own language and the interface is already popular in Mac, Solaris, FreeBSD, and to some extent linux and NetBSD.

Brendan Gregg is famous for his approach measuring performance and his flamegraphs.

]]> By: Justin Sherrill https://www.dragonflydigest.com/2017/08/07/new-mechanism-kcollect/comment-page-1/#comment-486670 Tue, 08 Aug 2017 03:46:51 +0000 https://www.dragonflydigest.com/?p=20061#comment-486670 Does DTrace do the same thing?

]]> By: Anonymous https://www.dragonflydigest.com/2017/08/07/new-mechanism-kcollect/comment-page-1/#comment-486669 Tue, 08 Aug 2017 03:21:53 +0000 https://www.dragonflydigest.com/?p=20061#comment-486669 Pedro. Can you explain more. I’m not following.

]]> By: Pedro https://www.dragonflydigest.com/2017/08/07/new-mechanism-kcollect/comment-page-1/#comment-486668 Tue, 08 Aug 2017 03:10:16 +0000 https://www.dragonflydigest.com/?p=20061#comment-486668 Sounds misguided … ignorance of the DTrace way.

]]> By: New mechanism: kcollect – FreshBSD.com https://www.dragonflydigest.com/2017/08/07/new-mechanism-kcollect/comment-page-1/#comment-486667 Tue, 08 Aug 2017 01:28:00 +0000 https://www.dragonflydigest.com/?p=20061#comment-486667 […] Go to Source Author: Justin Sherrill […]

]]> By: Anonymous https://www.dragonflydigest.com/2017/08/07/new-mechanism-kcollect/comment-page-1/#comment-486666 Tue, 08 Aug 2017 00:51:36 +0000 https://www.dragonflydigest.com/?p=20061#comment-486666 I wonder why Matt thought it was necessary to add this functionality.

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