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NMICH1
Beginner
1,492 Views

Intel 750 : high read latency

Hello,

I am using a 400gb Intel 750 (pcie card) on a Z97 board.

Using AS SSD, I find that the read latency is about 4 times higher than what I see from reviews (0.08ms vs 0.02ms). The write latency is ok. The 0.02ms seems in line with the specs of the drive, so it appears that my system is slow.

I tried moving to the CPU lanes to see if that was a factor. As expected, I got a nice boost in seq read, but no change in latency :

Example from the web (Google image search for "intel 750 asssd") :

Any idea of what I should look for to obtain "normal" read latencies ? I tried disabling real-time protection in Windows Defender, but no change there.

Platform :

Windows 10 AU

NVME driver 1.7

Intel 4790k

16 Gb RAM

Maximus VII Hero (Z97)

Intel 750 400Gb

0 Kudos
13 Replies
idata
Community Manager
97 Views

Latenic,

 

 

We are going to check this for you and will advise very soon. In the mean time, if you have any further questions, please do not hesitate to contact us.

 

 

Best regards,

 

Aleki
NMICH1
Beginner
97 Views

Thanks !

I've tried disabling all the Windows file filters I could, but I couldn't get the latency to budge.

I ran a complete check using SSD Toolbox, the drive appears healthy.

idata
Community Manager
97 Views

Latenic,

 

 

Thank you for your time. Taking advantage of the direct path from the storage to the CPU by means of NVMe, the Intel®SSD 750 Series exhibits low latency of less than 20 μs for sequential accesses. See the http://www.intel.com/content/dam/www/public/us/en/documents/product-specifications/ssd-750-spec.pdf Intel® Solid-State Drive 750 Series Product Specification on page # 9 for more information.

 

 

For further information on this you can also check this documentation:http://www.intel.com/content/dam/support/us/en/documents/ssdc/hpssd/ssd-750/sb/intel_ssd_750_series_... Intel® Solid-State Drive 750 Series - Evaluation Guide from page # 13 on where it shows the method used by Intel for accurate results.

 

 

Please, let us know if this helped you.

 

 

Best regards,

 

Aleki
NMICH1
Beginner
97 Views

Hello,

This did not help.

Unless I'm mistaken, the linked guide only shows how to measure throughput - not latency (in fact, in the screenshots in the guide, average latency is above 3ms).

Is there a guide on how to measure the 20 μs latency ?

(I ran the iometer setup in the guide, the result is below)

idata
Community Manager
97 Views

Latenic,

 

 

In this case, could please provide the logs from the Intel Solid State Drive Toolbox so we can take a look? Here is the link to it: https://downloadcenter.intel.com/download/26085/Intel-Solid-State-Drive-Toolbox Intel® Solid State Drive Toolbox. We are looking forward to hearing from you soon.

 

 

Best regards,

 

Aleki
NMICH1
Beginner
97 Views

Hello,

Is that the file you get when clicking "Export" ? (Attached to this post). Or is there a location I should get the file from ?

Best regards,

idata
Community Manager
97 Views

Latenic,

 

 

Thank you for the logs. We are going to analyze and will get back to you as soon as possible.

 

 

Best regards,

 

Aleki
idata
Community Manager
97 Views

Latenic,

 

 

Thank you very much for your time. Upon analyzing the logs you have sent to us. We could see the the drive is negotiating with only 0x2 link speed and should negotiate with 0x3 as it is PCIe* 3.0. At this point, it is important to check if it is connected to the right slot as we could see that the drive us running the latest firmware.

 

 

Please, also, make sure you have the latest BIOS update. According to the motherboard manual, slots No. # 2 and No. # 4 are the recommended ones for this drive. You can confirm this on Chapter 1 >> Motherboard overview item 1.2.5 (Expansion Slots) pages: 1-24 of this manual. For your convenience, here is a link to it: http://dlcdnet.asus.com/pub/ASUS/mb/LGA1150/MAXIMUS-VII-HERO/E9192_Maximus_Vii_Hero.pdf Asus* Maximus VII Hero Motherboard Manual.

 

 

As soon as you have tested, please let us if this worked for you.

 

 

Best regards,

 

Aleki
NMICH1
Beginner
97 Views

Hello,

Thanks for the investigation.

However as I indicated in my first post, moving to the CPU lanes (the recommended slot) does not change the latency (though of course it does increase max throughput).

Maybe what I'm seeing is not a real problem, but I'd really like to have an Intel validated way of measuring latency (maybe add a section in your Evaluation Guide regarding latency ?).

idata
Community Manager
97 Views

Latenic,

 

 

It is important to make sure you are connected to the right slot. The board contains:

 

2 x PCIe 3.0/2.0 x 16 slots (Red, Single at x16 or dual at x8/x8 mode)

 

1 xPCIe 2.0 x16 slot (Black, max. at x4 mode)

 

3 x PCIe 2.0 x1 slots

 

 

On Chapter 3 page 34, it shows the configuration, please, follow the instructions there and let us know if it worked for you. Unfortunately, as for a validation guide, thank you for your feedback, but there is no validation guide available.

 

 

Please let us know if this helped you.

 

 

Best regards,

 

Aleki

 

 

NMICH1
Beginner
97 Views

It did not.

As stated in my first post, I tried running the benchmark when connected to the CPU lanes (red slot). I verified that the card was operating in PCIE 3 mode. But the reported latency remained unchanged.

Best regards.

idata
Community Manager
97 Views

Latenic,

 

 

According to the logs you have sent, it says it is PCIe* gen 2. Please, check if you are running the latest BIOS firmware and also check if there isn't any settings in the BIOS that could be limiting the PCIe* version used on the slot.

 

 

Best regards,

 

Aleki
idata
Community Manager
97 Views

Latenic,

 

 

We haven't heard from you in while so we would like to know if you had the opportunity to try the steps we have provided previously.

 

 

Best regards,

 

Aleki
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