The flamegraphs are here:
https://drive.google.com/open?id=1vM-5wy4s-QhV2D3hBVh5bPgaqPqEKsMa
There are 11 of them.
Files out.svg to out4.svg are dtrace flamegraphs of reading when L2ARC has been
in use.
out5.svg to out10.svg are dtrace flamegraphs of usign nvmecontrol command - in
read mode
> On Aug 29, 2018, at 11:49 AM, w.kruzel via openzfs-developer
> wrote:
>
> I think yes, there is sufficient demand to have I/O at such level. What do
> you mean by higher rate for the same workload? If types of devices - I have
> tested two Intel nvme disks and one of them had a
I think yes, there is sufficient demand to have I/O at such level. What do you
mean by higher rate for the same workload? If types of devices - I have tested
two Intel nvme disks and one of them had a throughput limit on 1 thread at
about 225MB/s while the other had an output of 285MB/s
I shall
Are you sure that the demand on L2ARC is sufficient to create that I/O
rate? Do other devices for L2ARC provide a higher rate for the same work
load?
Sanjay
On Fri, Aug 24, 2018, 10:29 AM w.kruzel via openzfs-developer <
developer@lists.open-zfs.org> wrote:
> Thanks, Sanjay - I will try running
Thanks, Sanjay - I will try running it on FreeBSD and will post some flame
graphs here.
> Maybe I am doing it wrong but I am using NVMe for primary storage and ass
> tons of ram for arc.
In my case we went for capacity, and planning on having 36x10TB disks. With the
initial stage of 12x10TB
L2ARC uses the ZIO pipeline, just like everything else. Very parallel. But if
your workload isn’t parallel, then...
-- richard
> On Aug 23, 2018, at 7:03 PM, Jason Matthews wrote:
>
>
> In 1989 a 4mb stick of ram was like $800. RAM is cheap despite price fixing.
>
> Having recently
In 1989 a 4mb stick of ram was like $800. RAM is cheap despite price fixing.
Having recently maxed out the 64mb of RAM on my personal IPX in like 1994, I
remember telling Len Rose I can’t imagine having a gigabyte of RAM. He laughed
at me.
Now I sit on racks of systems with 768gb of RAM.
Not every board can take ass-tons of RAM, and DDR4 RAM prices have
gone markedly up in the last 2 years, not down. (There's even a fun
price-fixing lawsuit or two in the works.)
You'd also need to buy a decently high-end chip to exceed 128 GB of
RAM on your server.
So while I agree the need for
Maybe I am doing it wrong but I am using NVMe for primary storage and ass tons
of ram for arc.
I think L2ARC is relegated to the highly budget oriented plays these days as
RAM is s cheap. Buy some more ram and fooor-get-about it.
J.
Sent from my iPhone
> On Aug 23, 2018, at 1:07 PM,
Found this link for FreeBSD too
http://www.brendangregg.com/blog/2015-03-10/freebsd-flame-graphs.html
-Sanjay
On 8/23/18 1:02 PM, Sanjay Nadkarni wrote:
Would be useful if you could get flamegraphs when you run into this.
See https://github.com/brendangregg/FlameGraph
Once we have that,
Would be useful if you could get flamegraphs when you run into this. See
https://github.com/brendangregg/FlameGraph
Once we have that, the we can have a better understanding of what's
going on and we can dtrace it further to figure it out.
-Sanjay
On 8/23/18 5:47 AM, w.kruzel via
It's interesting what you said, as I have two examples (both with different
Intel nvme disks) that show otherwise.
Being nvme, I was expecting read performance from L2ARC at 2GB/s+ levels, yet I
only get ~200MB/s read speeds when I certainly know it is being read from L2ARC.
When tested
> On Aug 22, 2018, at 11:06 AM, w.kruzel via openzfs-developer
> wrote:
>
> I would really like to know if the L2ARC read process single-threaded.
It is not single threaded.
-- richard
> Also how can we make it multi threaded and is it possible?
>
> Thanks,
> Wojciech
> openzfs
I would really like to know if the L2ARC read process single-threaded.
Also how can we make it multi threaded and is it possible?
Thanks,
Wojciech
--
openzfs: openzfs-developer
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