Method for efficient non-virtual main memory management

An improved dual image allocation method for operating non-virtual main memory manager using swapin and swapout operations to allocate and un-allocate space in a non-virtual main memory for one or more segments of one or more process images residing on a swap device and ready to be executed in a computer processing system that includes one or more processors sharing the main memory and the swap device wherein the segments require space of varying sizes and all of the segments for a process image must be resident in the main memory before the process image can be executed by the computer processing system, the steps of the improved method comprising:

• performing a swapin allocation operation to allocate contiguous space in the main memory to at least one segment of one process image residing on the swap device,
• the swapin allocation operation including the step of checking to determine if the one segment already has been allocated space in the main memory,
• if so, performing another swapin allocation operation to allocate contiguous space in the main memory to another segment of the one process image,
• if not, checking for an un-allocated contiguous space in the main memory large enough to store the entire one segment, and allocating that space to the one segment and copying the segment to the main memory,
• in the event that space is allocated to the one segment, retaining an image of the segment on the swap device so as to create a dual image allocation whereby it is only necessary to un-allocate the space allocated to the one segment, without copying the segment to the swap device in the event the segment is to be removed from main memory by a swapout operation.

An improved split image swapin method for operating a non-virtual main memory manager using swapin and swapout operations to allocate and un-allocate space in non-virtual main memory for one or more segments of one or more process images residing on a swap device and ready to be executed in a computer processing system that includes one or more processors sharing the main memory and the swap device wherein the segments require space of varying sizes and all of the segments for a process image must be resident in the main memory before the process image can be executed by the computer processing system, the steps of the improved method comprising:

• determining whether there is un-allocated space in the main memory of sufficient size to contain a segment to be swapped into the main memory,
• if there is un-allocated space in the main memory of sufficient size to contain the segment to be swapped into the main memory, then allocating that space to the segment,
• if there is not sufficient un-allocated space in the main memory to contain the segment to be swapped into the main memory, then determining whether the segment may be divided into split segments according to a pre-determined criteria and
• if the segment may be divided into split segments, then splitting the segment into at least two split segments, at least one of the split segments being allocated a memory size corresponding to an un-allocated contiguous space in the main memory.

An improved method for operating a non-virtual main memory manager using swapin and swapout operations to allocate and un-allocate space in non-virtual main memory for one or more segments of one or more process images residing on a swap device in a computer processing system that includes one or more processors sharing the main memory and the swap device wherein the segments require space of varying sizes and all of the segments for a process image must be resident in the main memory before the process image can be executed by the computer processing system, and wherein the main memory manager performs a swapin operation for the segments of a selected swapin process image ready to execute and performs a swapout operation for the segments of one or more process images currently stored in the main memory, the steps of the improved method comprising:

• determining for each segment of the selected swapin process image if space in main memory has or has not been allocated for that segment,
• in the event that space in the main memory has not been allocated for a segment, then determining if sufficient contiguous space in the main memory can or cannot be allocated for that segment,
• in the event that sufficient contiguous space in the main memory cannot be allocated for that segment, then attempting to allocate space in the main memory for that segment by allowing segments shared by more than one process image to be forced out of the main memory.

An improved swapout coalescing method for operating a non-virtual main memory manager using swapin and swapout operations to allocate and un-allocate space in non-virtual main memory for one or more segments of one or more process images residing on a swap device and ready to be executed in a computer processing system that includes one or more processors sharing the main memory and the swap device and wherein the segments require space of varying sizes and all of the segments for a process image must be resident in the main memory before the process image can be executed by the computer processing system, and wherein the main memory manager performs a swapin operation for the segments of a selected process image ready to execute and performs a swapout operation for the segments of one or more process images currently stored in the main memory, the steps of the improved method comprising:

• allocating a space on the swap device of a size which is large enough to contain a segment of a selected swapout segment of a process image,
• determining if the selected swapout segment has been divided into two or more split segments,
• in the event that the selected swapout segment has split segments, coalescing the split segments into the space allocated on the swap device, and
• in the event that the segment has no split segments, moving the segment into the allocated space on the swap device.

In a computer processing system, an efficient method for managing memory allocation of a non-virtual main memory to a plurality of processes to be executed by one or more processors in the computer processing system, each process having a process image including one or more segments that are stored in the main memory or in a swap device, each segment having a defined memory size and containing a type of information associated with that process, wherein the memory size of different segments is variable and all of the segments of a process must be resident in the non-virtual main memory in order for that process to be executed by the computer processing system, the method comprising the processor-implemented steps of:

• (a) selecting a swapin process to be swapped into the main memory from the swap device;
• (b) for each segment of the process image of the swapin process, performing the steps of:
• (b1) determining whether the segment has been allocated space in the main memory;
• (b2) if the segment has not been allocated space in the main memory, determining whether there are any un-allocated contiguous spaces in the main memory;
• (b3) if there are no un-allocated contiguous spaces in the main memory, executing a swapout procedure to create one or more un-allocated contiguous spaces in the main memory;
• and
• (b4) if there is at least one un-allocated contiguous space in the main memory, attempting to allocate contiguous space in the main memory for the segment, including the steps of:
• (b41) allocating space to the segment if there is sufficient un-allocated contiguous space in the main memory for the memory size of the segment,
• (b42) splitting the segment into two or more split segments if there is not sufficient contiguous space in the main memory to allocate for the memory size of the segment and if the segment contains one of a predetermined set of types of information which can be split, such that at least one of the split segments is of a memory size that sufficient un-allocated contiguous space in the main memory can be allocated to that split segment, and
• (b43) executing the swapout procedure if there is not sufficient un-allocated contiguous space in the main memory for the memory size of the segment or one of the split segments and repeating steps (b41)-(b42);
• and
• (c) if all of the segments of the swapin process were allocated space in the main memory, copying all of the segments of the process image from the swap device to the main memory and adding the process to a run queue of processes to be executed by one or more of the processors.

In a computer processing system, a split segment method for managing memory allocation of a non-virtual main memory to a plurality of processes to be executed by one or more processors in the computer processing system, each process including one or more segments that are stored in the main memory or in a swap device, each segment having a defined memory size and containing a type of information associated with that process, wherein the memory size of different segments is variable and all of the segments of a process must be resident in the non-virtual main memory in order for that process to be executed by the computer processing system, the method comprising the processor-implemented steps of:

• during a swapin allocation operation wherein contiguous space in the main memory is allocated to one or more of the segments of a process that are to be swapped into the main memory from the swap device,
• attempting to split one or more of the segments of the process into two or more split segments if there is not sufficient contiguous space in the main memory to allocate for the memory size of the segment and if the segment contains one of a predetermined set of types of information which can be split, such that at least one of the split segments will be of a memory size that sufficient contiguous space in the main memory can be allocated to that split segment;
• and
• during a swapout operation wherein one or more of the segments of a process are to be swapped out of the main memory to the swap device,
• coalescing any split segments of a segment of the process into the memory size of that segment as the segments are transferred to the swap device,
• whereby utilization of the main memory is enhanced by splitting the split segments into memory sizes that correspond to contiguous memory spaces in the main memory that are available each time a swapin allocation operation is performed for a process.