On Sun, Mar 19, 2017 at 3:36 AM, Alan Mackenzie <a...@muc.de> wrote:
> Hello, Gentoo.
>
> I've just bought myself a Samsung NVMe 960 EVO M.2 SSD.
> <snip>
> Some timings:
>
> An emerge -puND @world (when there's nothing to merge) took 38.5s. With
> my mirrored HDDs, this took 45.6s. (Though usually it takes nearer a
> minute.)
>
> An emerge of Firefox took 34m23s, compared with 37m34s with the HDDs.
> The lack of the sound of the HDD heads moving was either disconcerting
> or a bit of a relief, I'm not sure which.
>
> Copying my email spool file (~110,000 entries, ~1.4 GB) from SSD -> SSD
> took 6.1s. From HDD RAID -> HDD RAID it took 30.0s.
>
> <snip>
>
I was also hoping for more speed up when i got mine, but of course it only
helps with the system is IO bound. Its great for loading VMs.
It may be mandatory with NVM, but you can check multiqueue is setup/working
with;
# cat /proc/interrupts | egrep '(CPU|nvm)'
CPU0 CPU1 CPU2 CPU3 CPU4
CPU5 CPU6 CPU7
30: 21596 0 0 0 0
0 0 0 PCI-MSI 1572864-edge nvme0q0, nvme0q1
40: 0 12195 0 0 0
0 0 0 PCI-MSI 1572865-edge nvme0q2
41: 0 0 12188 0 0
0 0 0 PCI-MSI 1572866-edge nvme0q3
42: 0 0 0 13696 0
0 0 0 PCI-MSI 1572867-edge nvme0q4
43: 0 0 0 0 11698
0 0 0 PCI-MSI 1572868-edge nvme0q5
44: 0 0 0 0 0
45820 0 0 PCI-MSI 1572869-edge nvme0q6
45: 0 0 0 0 0
0 10917 0 PCI-MSI 1572870-edge nvme0q7
46: 0 0 0 0 0
0 0 12865 PCI-MSI 1572871-edge nvme0q8
If its not setup there'll be just a single IRQ/core handling all the IO.
FWIW
# hdparm -tT /dev/nvme0n1
/dev/nvme0n1:
Timing cached reads: 9884 MB in 2.00 seconds = 4945.35 MB/sec
Timing buffered disk reads: 4506 MB in 3.00 seconds = 1501.84 MB/sec
