Clearing specified blocks of main storage

Patent metadata

Field	Value
Publication number	US-9727335-B2
Application number	US-201615014063-A
Country	US
Kind code	B2
Filing date	Feb 3, 2016
Priority date	Jan 27, 2015
Publication date	Aug 8, 2017
Grant date	Aug 8, 2017

Abstract

Embodiments of the present invention provide systems and methods for clearing specified blocks of main storage. In one embodiment, an EADM start subchannel is executed. The instructions of the execution of the EADM start subchannel may include a SAP receiving an ADM request block, which specifies a main-storage-clearing operation command. The address and size of a block of main memory to be cleared by the SAP is specified in an MSB designated by the ADM request block.

First claim

What is claimed is:

1. A method in a data processing system comprising:
determining, by a processor, from an instruction stream, an extended asynchronous data mover (EADM) start subchannel instruction, wherein the EADM start subchannel instruction comprises: a subsystem identification operand and an EADM operation request block operand configured to designate a location of an EADM operation request block;
executing, by the processor, the EADM start subchannel instruction, wherein executing the EADM start subchannel instruction comprises notifying a system assist processor (SAP), wherein the SAP comprises:
an equivalent architecture as a CPU on which operating systems and application programs execute; and
performing memory clearing operations in a similar manner as the CPU on which operating systems and application programs execute;

receiving, by the SAP, an asynchronous data mover (ADM) request block; determining, by the SAP, whether the ADM request block specifies a main-storage-clearing operation command, wherein the main-storage-clearing operation command operates asynchronously from a program on a CPU;
responsive to determining the ADM request block specifies the main-storage-clearing operation command, obtaining one or more move specification blocks (MSBs), wherein an address associated with the one or more MSBs is designated by the ADM request block;
determining, by the SAP, based on the one or more MSBs, an address and a size of a main storage block to clear;
responsive to determining the address and the size of the main storage block, clearing, by the SAP, the main storage block, wherein if the SAP is associated with a predetermined time period for clearing the main storage block, then a set of partially completed instructions are placed on a queue by the SAP, to continue the clearing of the main storage block at a later time;
responsive to clearing, by the SAP, the main storage block, notifying, asynchronously, the CPU, when the SAP successfully completes the main-storage-clearing operation command;
responsive to determining that the main-storage-clearing operation command did not complete successfully, providing an indication, in an ADM response block, of an error associated with at least one of: a request block, the one or more MSBs, and a memory access;
responsive to executing the EADM start subchannel instruction and notifying the SAP, monitoring, by the processor, the main storage clearing operations;
responsive to monitoring the main storage clearing operations, receiving, by the processor, a set of frequency statistics associated with the main-storage clearing operations, wherein the set of frequency statistics comprises:
a quantity of blocks cleared,
a size of the blocks cleared, and
a reason for clearing the specified blocks;

responsive to receiving the set of frequency statistics, determining, by the processor, whether it is more efficient to use a combination of both the CPU memory cleaning operation and the SAP main storage cleaning operation, to clear the main storage block, wherein determining whether the combination of both the CPU the SAP is more efficient comprises:
analyzing, by the processor, the set of frequency statistics and a current workload in the CPU; and

responsive to determining, it is more efficient to use a combination of both the CPU and the SAP to clear the main storage block, continuously, at predetermined intervals, analyzing by the processor, the set of frequency statistics to identify a breakpoint by comparing if it is more effective to use the CPU to when it is more effective to use the SAP for main storage clearing operations.

Assignees

• IBM
• Int Business Machines Incorporated

Inventors

• Coneski Anthony F
• Glendening Beth A
• Greiner Dan F
• Sutton Peter G
• Tuttle Scott B
• Tzortzatos Elpida

Classifications

• G06F12/023 Primary

  Free address space management · CPC title

• G06F3/0617

  in relation to availability · CPC title

• G06F9/5077

  Logical partitioning of resources; Management or configuration of virtualized resources (specific details on emulation or internal functioning of virtual machines G06F9/455) · CPC title

• G06F3/065

  Replication mechanisms · CPC title

• G06F2212/1044

  Space efficiency improvement · CPC title