Patents by Inventor Charalampos Pozidis

Charalampos Pozidis has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 11295236
    Abstract: Computer-implemented methods are provided for implementing training of a machine learning model in a heterogeneous processing system that includes a host computer operatively interconnected to an accelerator unit. The training operation involves an iterative optimization process for optimizing a model vector defining the model. Such a method includes, in the host computer, storing a matrix of training data and partitioning the matrix into a plurality of batches of data vectors. For each of successive iterations of the optimization process, a selected subset of the batches is provided to the accelerator unit. In the accelerator unit, each iteration of the optimization process is performed to update the model vector in dependence on vectors in the selected subset for that iteration. In the host computer, batch importance values are calculated for respective batches. The batch importance value is dependent on contributions of vectors in that batch to sub-optimality of the model vector.
    Type: Grant
    Filed: December 10, 2018
    Date of Patent: April 5, 2022
    Assignee: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Celestine Duenner, Thomas Parnell, Charalampos Pozidis
  • Patent number: 11264103
    Abstract: A computer-implemented method, according to one embodiment, includes: determining a current operating state of a block of memory. The block includes more than one type of page therein, and at least one read voltage is associated with each of the page types. The current operating state of the block is further used to produce a hybrid calibration scheme for the block which identifies a first subset of the read voltages, and a second subset of the read voltages. The read voltages in the second subset are further organized in one or more groupings. A unique read voltage offset value is calculated for each of the read voltages in the first subset, and a common read voltage offset value is also calculated for each grouping of read voltages in the second subset.
    Type: Grant
    Filed: August 28, 2019
    Date of Patent: March 1, 2022
    Assignee: International Business Machines Corporation
    Inventors: Nikolaos Papandreou, Charalampos Pozidis, Nikolas Ioannou, Roman Alexander Pletka, Radu Ioan Stoica, Sasa Tomic, Timothy Fisher, Aaron Daniel Fry, Andrew D. Walls
  • Patent number: 11238295
    Abstract: Processing a digital image in a distributed computing environment comprising a communications network interconnecting two or more computing nodes. A segmentation of the digital image into two or more image segments is determined. For each of the image segments, a number of non-background pixels comprised by the image segment is determined. An assignment of each of the image segments to one of the computing nodes is determined. The determination of the assignment may include balancing, based on the number of non-background pixels determined for each of the image segments, the workload of the assigned computing nodes responsive to processing the image segments. Each of the assigned computing nodes may be caused to process the image segments assigned to the computing node.
    Type: Grant
    Filed: March 19, 2019
    Date of Patent: February 1, 2022
    Assignee: International Business Machines Corporation
    Inventors: Nikolaos Papandreou, Andreea Anghel, Milos Stanisavljevic, Charalampos Pozidis
  • Patent number: 11222054
    Abstract: Two sets X2 and X1 of histograms of words, and a vocabulary V are accessed. Each of the two sets is representable as a sparse matrix, each row of which corresponds to a histogram. Each histogram is representable as a sparse vector, whose dimension is determined by a dimension of the vocabulary. Two phases compute distances between pairs of histograms. The first phase includes computations performed for each histogram and for each word in the vocabulary to obtain a dense, floating-point vector y. The second phase includes computing, for each histogram, a sparse-matrix, dense-vector multiplication between a matrix-representation of the set X1 of histograms and the vector y. The multiplication is performed to obtain distances between all histograms of the set X1 and each histogram X2[j]. Distances between all pairs of histograms are obtained, based on which distances between documents can subsequently be assessed.
    Type: Grant
    Filed: March 12, 2018
    Date of Patent: January 11, 2022
    Assignee: International Business Machines Corporation
    Inventors: Kubilay Atasu, Cesar Berrospi Ramis, Nikolas Ioannou, Thomas Patrick Parnell, Charalampos Pozidis, Vasileios Vasileiadis
  • Patent number: 11221911
    Abstract: A memory controller for recovering data due to transient effects of nonvolatile memory is provided. A memory controller receives a read request for a page stored in the nonvolatile memory. The memory controller issues a first read command. The memory controller records a time stamp for the first read command. In response to a failure during the first read command, the memory controller waits for a delay after the recorded time stamp and the memory controller issues a second read command to the page, wherein the second read command applies a read voltage offset that is dependent on the delay between the first read command and the second read command and at least one other parameter.
    Type: Grant
    Filed: October 11, 2019
    Date of Patent: January 11, 2022
    Assignee: International Business Machines Corporation
    Inventors: Nikolaos Papandreou, Charalampos Pozidis, Nikolas Ioannou, Roman Alexander Pletka, Sasa Tomic
  • Patent number: 11188261
    Abstract: Aspects of the present invention disclose a method, computer program product, and system for controlling operation of an array of non-volatile memory cells comprising cells which are selectively configurable for single-bit and multibit storage. The method includes a memory controller selectively configuring the array for operation in a hybrid mode, in which the array comprises both cells configured for single-bit storage and cells configured for multibit storage, and a multibit mode in which all cells in the array are configured for multibit storage. The method further includes the memory controller dynamically switching between the hybrid and multibit mode configurations of the array corresponding to array capacity-usage traversing a defined threshold level associated with enhance endurance of the array.
    Type: Grant
    Filed: November 18, 2019
    Date of Patent: November 30, 2021
    Assignee: International Business Machines Corporation
    Inventors: Nikolaos Papandreou, Roman Alexander Pletka, Radu Ioan Stoica, Nikolas Ioannou, Sasa Tomic, Charalampos Pozidis
  • Patent number: 11182089
    Abstract: A computer-implemented method, according to one embodiment, includes: determining whether a number of blocks included in a first ready-to-use (RTU) queue is in a first range of the first RTU queue. In response to determining that the number of blocks included in the first RTU queue is in the first range, a determination is made as to whether a number of blocks included in a second RTU queue is in a second range of the second RTU queue. Moreover, in response to determining that the number of blocks included in the second RTU queue is not in the second range, valid data is relocated from one of the blocks in a first pool which corresponds to the first RTU queue. The block in the first pool is erased, and transferred from the first pool to the second RTU queue which corresponds to a second pool.
    Type: Grant
    Filed: July 1, 2019
    Date of Patent: November 23, 2021
    Assignee: International Business Machines.Corporation
    Inventors: Roman Alexander Pletka, Radu Ioan Stoica, Sasa Tomic, Nikolaos Papandreou, Nikolas Ioannou, Aaron Daniel Fry, Timothy Fisher, Charalampos Pozidis, Andrew D. Walls
  • Publication number: 20210334709
    Abstract: The present invention is notably directed to a computer-implemented method of training a cognitive model. The cognitive model includes decision trees as base learners. The method is performed using processing means to which a given cache memory is connected, so as to train the cognitive model based on training examples of a training dataset. The cognitive model is trained by running a hybrid tree building algorithm, so as to construct the decision trees and thereby associate the training examples to leaf nodes of the constructed decision trees, respectively. The hybrid tree building algorithm involves a first routine and a second routine. Each routine is designed to access the cache memory upon execution. The first routine involves a breadth-first search tree builder, while the second routine involves a depth-first search tree builder.
    Type: Application
    Filed: April 27, 2020
    Publication date: October 28, 2021
    Inventors: Nikolas Ioannou, Andreea Anghel, Thomas Parnell, Nikolaos Papandreou, Charalampos Pozidis
  • Patent number: 11152059
    Abstract: Performing a calibration of a NAND flash memory block that is in an open state. An open state of the NAND flash memory block is detected, the NAND flash memory block comprising a plurality of memory pages, each of which comprising a plurality of memory cells. A group of pages of the NAND flash memory block being in an open state having comparable characteristics is identified. A calibration of read voltage values to pages of the group of identified pages is performed.
    Type: Grant
    Filed: November 13, 2019
    Date of Patent: October 19, 2021
    Assignee: International Business Machines Corporation
    Inventors: Nikolaos Papandreou, Roman A. Pletka, Sasa Tomic, Nikolas Ioannou, Charalampos Pozidis, Aaron D. Fry, Timothy Fisher
  • Patent number: 11151053
    Abstract: A computer-implemented method, according to one embodiment, is for maintaining heat information of data while in a cache. The computer-implemented method includes: transferring data from non-volatile memory to the cache, such that the data is stored in a first page in the cache. Previous read and/or write heat information associated with the data is maintained by preserving one or more bits in a hash table which correspond to the data in the first page. Moreover, the data is destaged from the first page in the cache to the non-volatile memory, and the one or more bits in the hash table which correspond to the data are updated to reflect current read and/or write heat information associated with the data.
    Type: Grant
    Filed: August 7, 2019
    Date of Patent: October 19, 2021
    Assignee: International Business Machines Corporation
    Inventors: Nikolas Ioannou, Nikolaos Papandreou, Roman Alexander Pletka, Sasa Tomic, Radu Ioan Stoica, Timothy Fisher, Aaron Daniel Fry, Charalampos Pozidis, Andrew D. Walls
  • Patent number: 11146293
    Abstract: A memory system, Reed Solomon (“RS”) Decoder, and method for decoding Reed-Solomon codewords includes: a Syndrome Computation engine configured as a first stage of a pipeline for receiving the RS codeword and computing one or more Syndromes; an initialization unit for providing initialization values for a key equation solver engine that generates the errata locator polynomial and the errata magnitude polynomial configured as a second stage; and as a third stage a Chien Search engine for receiving the error locator polynomial and determining the one or more locations of the one or more erasures and random errors in the received RS codeword and an error-value evaluation (“EE”) engine for receiving the errata magnitude polynomial and determining the one or more magnitudes of the one or more erasures and random errors in the RS received codeword.
    Type: Grant
    Filed: March 10, 2020
    Date of Patent: October 12, 2021
    Assignee: International Business Machines Corporation
    Inventors: Milos Stanisavljevic, Thomas Mittelholzer, Nikolaos Papandreou, Charalampos Pozidis
  • Publication number: 20210303425
    Abstract: Data protection systems and techniques that include: receiving data for storage in a non-volatile memory (NVM) array having a total number of physical packages that includes a number of spare physical packages, wherein each one of the physical packages is mapped to one of a plurality of logical packages; storing a respective portion of component codewords on the non-spare physical packages; and in response to one of the non-spare physical packages failing, dynamically remapping the failed physical package to one of the logical packages mapped to one of the available spare physical packages. In an aspect, reading at least the failed physical package and inserting virtual zeros into the respective portion of the component codewords corresponding to the failed physical package; performing erasure decoding to recover the data from the failed package; and rewriting the recovered data from the failed package into the one of the available spare physical packages.
    Type: Application
    Filed: March 31, 2020
    Publication date: September 30, 2021
    Inventors: Charalampos Pozidis, Thomas Mittelholzer, Nikolaos Papandreou, Milos Stanisavljevic
  • Publication number: 20210288669
    Abstract: A memory system, Reed Solomon (“RS”) Decoder, and method for decoding Reed-Solomon codewords includes: a Syndrome Computation engine configured as a first stage of a pipeline for receiving the RS codeword and computing one or more Syndromes; an initialization unit for providing initialization values for a key equation solver engine that generates the errata locator polynomial and the errata magnitude polynomial configured as a second stage; and as a third stage a Chien Search engine for receiving the error locator polynomial and determining the one or more locations of the one or more erasures and random errors in the received RS codeword and an error-value evaluation (“EE”) engine for receiving the errata magnitude polynomial and determining the one or more magnitudes of the one or more erasures and random errors in the RS received codeword.
    Type: Application
    Filed: March 10, 2020
    Publication date: September 16, 2021
    Inventors: Milos Stanisavljevic, Thomas Mittelholzer, Nikolaos Papandreou, Charalampos Pozidis
  • Patent number: 11120882
    Abstract: A method of optimizing a read threshold voltage shift value for non-volatile memory units organized as memory pages may be provided. An ECC check is performed for active page reads. The method comprises, as part of the read operation, determining a status of the memory page, and reading a memory page with a current threshold voltage shift (TVS) value. Additionally, the method comprises, upon determining that a read memory page command passed an ECC check, returning corrected data read, and upon determining that the read memory page did not pass the ECC check, adjusting the current TVS value based on the status of the memory page to be read. Furthermore, the method comprises, while the read memory pages continues to not pass the ECC check, repeating the adjusting the current TVS value and the determining that the read memory page passes ECC check until a stop condition is met.
    Type: Grant
    Filed: August 24, 2018
    Date of Patent: September 14, 2021
    Assignee: International Business Machines Corporation
    Inventors: Nikolas Ioannou, Charalampos Pozidis, Sasa Tomic, Nikolaos Papandreou, Roman A. Pletka, Aaron D. Fry, Timothy Fisher
  • Publication number: 20210264320
    Abstract: In an approach for constructing an ensemble model from a set of base learners, a processor performs a plurality of boosting iterations, where: at each boosting iteration of the plurality of boosting iterations, a base learner is selected at random from a set of base learners, according to a sampling probability distribution of the set of base learners, and trained according to a training dataset; and the sampling probability distribution is altered: (i) after selecting a first base learner at a first boosting iteration of the plurality of boosting iterations and (ii) prior to selecting a second base learner at a final boosting iteration of the plurality of boosting iterations. A processor constructs an ensemble model based on base learners selected and trained during the plurality of boosting iterations.
    Type: Application
    Filed: February 25, 2020
    Publication date: August 26, 2021
    Inventors: Thomas Parnell, Andreea Anghel, Nikolas loannou, Nikolaos Papandreou, Celestine Mendler-Duenner, Dimitrios Sarigiannis, Charalampos Pozidis
  • Patent number: 11094383
    Abstract: A computer-implemented method, according to one embodiment, includes: detecting that a calibration of a first page group has been triggered, and evaluating a hierarchical page mapping to determine whether the first page group correlates to one or more other page groups in non-volatile memory. In response to determining that the first page group does correlate to one or more other page groups in the non-volatile memory, a determination is made as to whether to promote at least one of the one or more other page groups for calibration. In response to determining to promote at least one of the one or more other page groups for calibration, the first page group and the at least one of the one or more other page groups are calibrated. Moreover, each of the page groups includes one or more pages in non-volatile memory.
    Type: Grant
    Filed: August 24, 2018
    Date of Patent: August 17, 2021
    Assignee: International Business Machines Corporation
    Inventors: Nikolaos Papandreou, Sasa Tomic, Roman A. Pletka, Nikolas Ioannou, Charalampos Pozidis, Aaron D. Fry, Timothy J. Fisher
  • Patent number: 11086705
    Abstract: A computer-implemented method, according to one embodiment, includes: performing a first read of one or more pages in a first page region of a first block. In response to determining that the highest RBER experienced during the first read is not in a first predetermined range, a first calibration procedure is performed on the one or more pages. A second read of the one or more pages is performed. In response to determining that the highest RBER experienced during the second read is not in a second predetermined range, a second calibration procedure on the one or more pages is performed, and a third read of the one or more pages is performed. In response to determining that the highest RBER experienced during the third read is not in the second predetermined range, a reliability counter which corresponds to the first page region of the first block is incremented.
    Type: Grant
    Filed: March 18, 2019
    Date of Patent: August 10, 2021
    Assignee: International Business Machines Corporation
    Inventors: Nikolaos Papandreou, Roman A. Pletka, Sasa Tomic, Nikolas Ioannou, Charalampos Pozidis, Timothy J. Fisher, Aaron D. Fry
  • Publication number: 20210216470
    Abstract: A memory system and method for storing data in one or more storage chips includes: one or more memory cards each having a plurality of storage chips, and each chip having a plurality of dies having a plurality of memory cells; a memory controller comprising a translation module, the translation module further comprising: a logical to virtual translation table (LVT) having a plurality of entries, each entry in the LVT configured to map a logical address to a virtual block address (VBA), where the VBA corresponds to a group of the memory cells on the one or more memory cards, wherein each entry in the LVT further includes a write wear level count to track the number of writing operations to the VBA, and a read wear level count to track the number of read operations for the VBA mapped to that LVT entry.
    Type: Application
    Filed: March 26, 2021
    Publication date: July 15, 2021
    Inventors: Daniel Frank Moertl, Damir Anthony Jamsek, Andrew Kenneth Martin, Charalampos Pozidis, Robert Edward Galbraith, Jeremy T. Ekman, Abby Harrison, Gerald Mark Grabowski, Steven Norgaard
  • Patent number: 11056199
    Abstract: A computer-implemented method, according to one approach, includes: using a first calibration scheme to calibrate the given page in the block by calculating a first number of independent read voltage offset values for the given page. An attempt is made to read the calibrated given page, and in response to determining that an error correction code failure occurred when attempting to read the calibrated given page, a second calibration scheme is used to recalibrate the given page in the block. The second calibration scheme is configured to calculate a second number of independent read voltage offset values for the given page. An attempt to read the recalibrated given page is also made. In response to determining that an error correction code failure did occur when attempting to read the recalibrated given page, one or more instructions to relocate data stored in the given page are sent.
    Type: Grant
    Filed: October 30, 2019
    Date of Patent: July 6, 2021
    Assignee: International Business Machines Corporation
    Inventors: Nikolaos Papandreou, Charalampos Pozidis, Nikolas Ioannou, Roman Alexander Pletka, Radu Ioan Stoica, Sasa Tomic, Aaron Daniel Fry, Timothy Fisher
  • Patent number: 11048571
    Abstract: A computer-implemented method, according to one embodiment, includes: receiving a multi-page read request and predicting whether using a multi-plane read operation to read pages of storage space in memory which correspond to the multi-page read request will result in a bit error rate that is in a predetermined range. In response to predicting that using the multi-plane read operation to read the pages will not result in a bit error rate that is in the predetermined range, a threshold voltage shift (TVS) value is computed for the multi-plane read operation. Furthermore, the pages are read using the multi-plane read operation with the computed TVS. Other systems, methods, and computer program products are described in additional embodiments.
    Type: Grant
    Filed: December 12, 2018
    Date of Patent: June 29, 2021
    Assignee: International Business Machines Corporation
    Inventors: Nikolas Ioannou, Nikolaos Papandreou, Roman A. Pletka, Sasa Tomic, Charalampos Pozidis, Aaron D. Fry, Timothy J. Fisher, Kevin E. Sallese