FMS2018

TECHNOLOGY

Data have become critical to all aspects of computing life, which in turn introduces immense demands of large memory solutions in many industries and business. However, DRAMs may face a difficulty to expand their storage capacity due to the memory technology scaling limit. The data refreshing power of DRAM is another challenge in satisfying the requirements of large memory solutions. MEMRAY considers leveraging non-volatile memory (NVM) and builds a series of new memory controllers and hardware/software infrastructure that can connect NVM to processors via a conventional memory bus. These new memory solutions can offers a large memory capacity as well as data persistency in diverse computing domains. MEMRAY expects that the new memory solutions can change the conventional memory hierarchy and open a new door in computing by making target systems more power and energy efficient.


While there is an alternative solution to extend the memory capacity by utilizing NVM as storage, such solution is not the best owing to the block interface, incompatible with the conventional memory bus, and extremely long latency of NVM. For example, “NVM as Cache” adopts NVM as cache for system storage. This strategy can provide a larger memory capacity than DRAM and provide the data persistency. While this solution can be used for storage cache, the performance is still far from DRAM. Moreover, the solution requires an OS and file system support, which makes system complicated and in-energy efficient. On the other hand, “NVDIMM-N” is a standard persistent memory, offered by JEDEC. It integrates DRAM and NVM into a single DIMM module. In contrast to the NVM as Cache solution, NVDIMM-N module no needs OS and file system support since it can be accessed by conventional load/store instructions over the DRAM interface. However, NVM is invisible to processors, and the storage capacity of NVDIMM-N is limited by its internal DRAM.
The persistent NVDIMM technology, one of MEMRAY’s new memory solutions, addresses the shortcomings brought by these two strategies. The new memory controller of MEMRAY exposes the entire NVM storage capacity to processors over DRAM interface. This in turn removes the file system and OS requirement, while offering large storage space. MEMRAY’s memory controller also hides the long latency imposed by the underlying NVM and supports all persistent instructions, which can incarnate a persistent NVDIMM as persistent and large memory solution.

PRODUCT

PRAM CELL

MEMRAY’s persistent NVDIMM technology internally employs new PRAM by carefully considering all the PRAM operation features. Specifically, PRAM consists of a phase change material, which has two different states, amorphous and crystalline, each representing ‘0’ and ‘1’, respectively. When the applied temperature is higher than the melting temperature threshold (~600oC), the material changes to amorphous state. If the applied temperature is between the crystalline (~300oC) and the melting temperature threshold, the PRAM material changes to crystalline state. Changing between these two states requires a certain period time, which makes a write latency longer than DRAM. Since data in PRAM should be maintained in cases of a power failure, the persistency during all memory operations should be survived appropriately.

MEMRAY’s PERSISTENT NVDIMM CONTROLLER

The persistent NVDIMM controller, which is key of MEMRAY’s NVDIMM technology, employs PRAM and DRAM as NVM and internal cache, respectively. These low-level memory modules are connected to MEMRAY’s memory controller through a conventional DDR interface, which is the common communication method in a general computing system. To hide the long write latency imposed by PRAM, MEMRAY’s NVDIMM controller takes DRAM as a write inclusive cache, but provides data persistency. Specifically, when a write request is issued from CPU (e.g., a store instruction), the corresponding data is first stored in DRAM cache, which exhibits DRAM-like performance. Since the read latency of PRAM is relatively similar to DRAM, a read request (issued by a load instruction) is directly serviced from PRAM. To offer data persistency and manage a power failure case, MEMRAY’s NVDIMM controller supports persistent operations such as, Intel CLFLUSH and FENCE. In addition to these features, the NVDIMM controller employs a smart migration technology, which internally transfers data from DRAM to PRAM with almost zero overhead. MEMRAY’s persistent NVDIMM solution guarantees non-volatility and a stable read/write latency (similar to DRAM).

GENERAL SPECIFICATION

MEMRAY’s persistent NVDIMM technology can be one of the best DRAM alternatives by offering DRAM-comparable features and performance characteristics; The technology no needs to employ a new interface and extra hardware/software component by connecting the NVDIMM controller and heterogeneous devices over the DDR interface. MEMRAY’s technology also provides the data persistency by supporting all necessary CPU-side persistency operations, thereby removing the power failure and transaction Issues. The smart migration technology can address the volatile property issue that potentially exists in a hybrid memory type of NVDIMMs, which also help the data consistency and secure high reliability. MEMRAY’s NVDIMM technology improves write performance 12 times compared to pure-PRAM NVDIMM, while offering a same level of data persistency of the PRAM.

PERFORMANCE

MEMRAY’s persistent NVDIMM technology, referred to as P-NVDIMM in this evaluation, shortens the latency of PRAM-only memory system by 30 times, on average, and offers DRAM-like latency by executing a cloud service system workload (Yahoo! Cloud Servicing Benchmark, YCSB) and a database workload, HASHMAP. These examples exhibit a crystal clear evidence that MEMRAY’s persistent NVDIMM technology can successfully hide the long write latency of PRAM and realize the potential of DRAM replacement as a large and persistent memory solutions. Note that all these evaluations are executed without having a file system or OS support – by using conventional load/store instructions. This does mean that the NVDIMM controller does not lose the large capacity of PRAM but make all memory spaces of the underlying NVDIMM visible to processors, which can compete against a DRAM-based memory subsystem by offering a reasonable performance with the large memory capacity.

CONCLUSION

MEMRAY’s persistent NVDIMM technology and controller therein can be used in many computing systems as a persistent and large memory solution, as it supports DRAM-like performance, high density and data persistency. Database and key-value stores keep their data in main memory with our persistent NVDIMM technology. When a server that has hundreds GB of memory faces any failure, all in-memory data should be reconstructed and it can take from several minutes to hours to marshal the information from the underlying storage. MEMRAY’s new memory solution can address this case, and also save tremendous energy wasted by a swapping system and off-computer I/O traffic. In addition, real-time data analytics can improve processing bandwidth and satisfy diverse SLA and QoS requirements with MEMRAY’s persistent NVDIMM technology. Upcoming future computing systems that require more memory capacity and persistency can take many benefits from MEMRAY’s new memory solution.

COMPANY

MemRay is a fabless start-up pushing the boundaries of non-volatile memory and computing resources to help immense amounts of data into valuable insight-redefining how modern systems use information. The new memory controllers of MemRay, including Hybrid Persistent-NVDIMM and NVDIMM-P, enable a variety of systems to keep data close to a processor, beyond the data volumes that the current memory technology can maintain. In parallel, the many-core solutions of MemRay offer low-power energy-efficient data processing near non-volatile memory in diverse computing domains. These non-volatile memory and processor platforms of MemRay can tightly couple all the necessary hardware/software components in a single pot, which can introduce the true next generation of data-processing products.

PATENT

PATENT REGISTERED

1. “RESISTANCE SWITCHING MEMORY BASED COPROCESSOR AND COMPUTING DEVICE INCLUDING THE SAME”
Registered Country: Korea (Application No. 10-2016-0119517), (Date of Application: 2016.09.19), (Country to apply: Korea, USA, China)

2. “COMPUTING DEVICE, DATA TRANSFER METHOD BETWEEN COPROCESSOR AND NON-VOLATILE MEMORY, AND PROGRAM INCLUDING THE SAME”
Registered Country: USA (Application No. 10-2016-0017233), (Date of Application: 2016.02.15), (Country to apply: Korea, USA, China)

3. “MEMORY CONTROLLER, AND MEMORY MODULE AND PROCESSOR INCLUDING THE SAME”
Registered Country: USA (Application No. 10-2016-0068402), (Date of Application: 2016.06.01), (Country to apply: Korea, USA, China)

PATENT EXAMINED (Preferential Examination)

1. “FLASH-BASED ACCELERATOR AND COMPUTING DEVICE INCLUDING THE SAME”
(Application No. 10-2016-0041120), (Date of Application: 2016.04.04 ),(Country to apply: Korea (Preferential Examination), USA, China)

2. “FLASH-BASED STORAGE DEVICE AND COMPUTING DEVICE INCLUDIN THE SAME”
(Application No. 10-2016-005907), (Date of Application: 2016.05.13), (Country to apply: Korea (Preferential Examination), USA, China)

3. “MEMORY CONTROLLER, AND MEMORY MODULE AND PROCESSOR INCLUDING THE SAME”
(Application No. 10-2016-0068400), (Date of Application: 2016.06.01), (Country to apply: Korea (Preferential Examination), USA, China)

4. ”PARALLEL PROCESSING UNIT, COMPUTING DEVICE INCLUDING THE SAME, AND THREAD GROUP SCHEDULING METHOD”
(Application No. 10-2016-0119514), (Date of Application 2016.09.19), (Country to apply: Korea(Preferential Examination), USA, PCT)

5 “MAGNETORESISTIVE MEMORY MODULE AND COMPUTING DEVICE INCLUDING THE SAME”
(Application No. 10-2016-0143591), (Date of Application 2016.10.31), (Country to apply: Korea(Preferential Examination), USA, China)

6. ”RESISTENCE SWITCHING MEMORY BASED ACCELERATOR”
(Application No. 10-2017-0112840), (Date of Application 2017.9.4), (Country to apply: Korea(Preferential Examination), USA, China)

7. ”FLASH BASED ACCELERATOR AND COMPUTING DEVICE INCLUDING THE SAME”
(Application No. 10-2017-0114029), (Date of Application 2017.9.6), (Country to apply: Korea(Preferential Examination), USA, China)

8. “FLASH BASED STORAGE AND CONTROLLER THEREOFF”
(Application No. 10-2017-0152433), (Date of Application 2017.10.15), (Country to apply: Korea(Preferential Examination), USA, China)

9. ”Expanding Persistent Memory with Ultra-Low Latency Flash Archives”
(Application No. 10-2017-0116935), (Date of Application 2017. 12.6), (Country to apply: Korea(Preferential Examination))

10. “MEMORY CONTROLLING DEVICE AND MEMORY SYSTEM INCLUDING THE SAME”
(Application No. 10-2018-0067739) (Date of Application 2018-6-12) ,(Country to apply: Korea(Preferential Examination))

11. “MEMORY CONTROLLING DEVICE AND MEMORY SYSTEM INCLUDING THE SAME” (Smart Technology (Application No. 10-2018-0075930) (Date of Application 2018-6-29), (Country to apply: Korea(Preferential Examination))

CONTACT