System and method for dynamically adjusting read ahead values based upon memory usage

A computer-implemented method of managing memory pages, wherein the memory includes a number of used pages and a number of free pages, said method comprising:

• retrieving a freelist value corresponding to the current number of free pages;
• determining that the freelist value is less than a predetermined minimum value;
• dynamically altering settings used by a sequential access read ahead process in response to the detection, wherein the altered settings are adapted to decrease the allocation of free pages to the sequential access read ahead process, and wherein the altering includes decreasing a current maximum page ahead value, wherein the current maximum page ahead value corresponds to a maximum number of pages read by the sequential access read ahead process, and wherein the decreasing further includes:
• calculating a shift value based on the difference between the freelist value and the predetermined minimum value;
• and
• bit shifting a constant maximum page ahead value by the shift value, the bit shifting resulting in the current maximum page ahead value.

An information handling system comprising:

• one or more processors;
• a memory accessible by the processors;
• an operating system that controls the processors;
• a virtual memory manager, included with the operating system, that manages use of the memory;
• a nonvolatile storage area managed by the operating system and including a disk swap area used by the virtual memory manager;
• a sequential access read ahead process performed by the operating system adapted to pre-fetch data being sequentially read from file stored in the nonvolatile storage area;
• memory conservation software used by the virtual memory manager, the software effective to:
• detect that a memory being managed by a virtual memory manager is constrained;
• dynamically alter settings used by the sequential access read ahead process in response to the detection, wherein the altered settings are adapted to conserve memory used by the sequential access read ahead process, and wherein the software is further effective to decrease a maximum page ahead value, wherein the maximum page ahead value corresponds to a maximum number of pages read by the sequential access read ahead process;
• execute the virtual memory manager for a time interval after decreasing the maximum page ahead value;
• determine that the memory is less constrained after the time interval has elapsed;
• and
• increase the maximum page ahead value in response to the determination.

An information handling system comprising:

• one or more processors;
• a memory accessible by the processors;
• an operating system that controls the processors;
• a virtual memory manager, included with the operating system, that manages use of the memory;
• a nonvolatile storage area managed by the operating system and including a disk swap area used by the virtual memory manager;
• a sequential access read ahead process performed by the operating system adapted to pre-fetch data being sequentially read from file stored in the nonvolatile storage area;
• memory conservation software used by the virtual memory manager, the software effective to:
• retrieve a freelist value corresponding to the current number of free pages;
• determine that the freelist value is less than a predetermined minimum value;
• dynamically alter settings used by a sequential access read ahead process in response to the detection, wherein the altered settings are adapted to decrease the allocation of free pages to the sequential access read ahead process, and wherein the altering includes decreasing a current maximum page ahead value, wherein the current maximum page ahead value corresponds to a maximum number of pages read by the sequential access read ahead process, wherein the decreasing includes:
• calculating a shift value based on the difference between the freelist value and the predetermined minimum value;
• and
• bit shifting a constant maximum page ahead value by the shift value, the bit shifting resulting in the current maximum page ahead value.

A computer program product stored on a computer operable media, said computer program product comprising:

• means for detecting that a memory being managed by a virtual memory manager is constrained;
• means for dynamically altering settings used by a sequential access read ahead process in response to the detection, wherein the altered settings are adapted to conserve memory used by the sequential access read ahead process, and wherein the means for altering includes means for decreasing a maximum page ahead value, wherein the maximum page ahead value corresponds to a maximum number of pages read by the sequential access read ahead process;
• means for executing the virtual memory manager for a time interval after decreasing the maximum page ahead value;
• means for determining that the memory is less constrained after the time interval has elapsed;
• and
• means for increasing the maximum page ahead value in response to the determination.

A computer-implemented computer program product for managing memory pages, wherein the memory includes a number of used pages and a number of free pages, said computer program product comprising:

• means for retrieving a freelist value corresponding to the current number of free pages;
• means for determining that the freelist value is less than a predetermined minimum value;
• means for dynamically altering settings used by a sequential access read ahead process in response to the detection, wherein the altered settings are adapted to decrease the allocation of free pages to the sequential access read ahead process, and wherein the means for altering includes means for decreasing a current maximum page ahead value, wherein the current maximum page ahead value corresponds to a maximum number of pages read by the sequential access read ahead process, and wherein the means for decreasing includes:
• means for calculating a shift value based on the difference between the freelist value and the predetermined minimum value;
• and
• means for bit shifting a constant maximum page ahead value by the shift value, the bit shifting resulting in the current maximum page ahead value.