US 7,734,842 B2Granted

Computer-implemented method, apparatus, and computer program product for managing DMA write page faults using a pool of substitute pages

AssigneeInternational Business Machines Corporation

InventorsRichard Louis Arndt, Steven Mark Thurber

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Abstract

A computer-implemented method, apparatus, and computer program product are disclosed for managing direct memory access (DMA) write page faults using a pool of substitute pages. A computer system platform resolves a DMA write page fault for a page that is dedicated to an Input/Output (I/O) adapter. The I/O adapter attempts to write DMA data to the page. A determination is made that the page is unavailable for writing. The DMA data is then written to data locations in a substitute page that was selected from the pool of substitute pages. A flag is then set in a flag location for each one of the data locations. The flag locations correspond to the data locations. When a flag is set, the flag indicates that DMA write data is present in the data location that corresponds to that flag's flag location.

Claims20

Dependent claims

A computer-implemented method for resolving a direct memory access (DMA) write page fault for a page that is dedicated to an Input/Output (I/O) adapter, said page dedicated to remain available for use by said I/O adapter, said computer-implemented method comprising:

attempting, by said I/O adapter, to write DMA data to said page;
responsive to said I/O adapter attempting to write DMA data to said page, identifying a particular entry in an address validation and translation table that is associated with said page, wherein each entry in the address validation and translation table includes an address field in which is stored an address and a control field in which is stored a current control setting;
reading the current control setting that is associated with said page from said particular entry,
in response to reading the current control setting, processing said attempt to write DMA data to said page according to said current control setting;
and
responsive to a DMA write fault occurring while processing said attempt:
writing said DMA data to only a subset of all data locations included in a substitute page, wherein said subset of data locations includes fewer than all data locations included in said substitute page, and further wherein said substitute page and said page include the same number of data locations;
and
setting a flag in a flag location that corresponds to each one of said subset of data locations, wherein the flag indicates that DMA write data is present in each one of said subset of data locations.

6 more elements

A computer program product that is stored in a computer-readable medium that includes program code, which when executed, performs the action of:

attempting, by said I/O adapter, to write DMA data to said page;
responsive to said I/O adapter attempting to write DMA data to said page, identifying a particular entry in an address validation and translation table that is associated with said page, wherein each entry in the address validation and translation table includes an address field in which is stored storing an address and a control field in which is stored a current control setting;
reading the current control setting that is associated with said page from said particular entry;
in response to reading the current control setting, processing said attempt to write DMA data to said page according to said current control setting;
and
responsive to a DMA write fault occurring while processing said attempt:
writing said DMA data to only a subset of all data locations included in a substitute page, wherein said subset of data locations includes fewer than all data locations included in said substitute page, and further wherein said substitute page and said page include the same number of data locations;
and
setting a flag in a flag location that corresponds to each one of said subset of data locations, wherein the flag indicates that DMA write data is present in each one of said subset of data locations.

6 more elements

Dependencies are inferred from the claim text.