Dynamic buffer reallocation

In a data storage system for handling a plurality of independet data transfers wherein each of said data transfers includes transferring blocks of data in a predetermined succession of such blocks of data;

• a data buffer having a plurality of allocatable data storage segments, each of said segments having a plurality of registers for storing one or more of said blocks of data;
• transfer means coupled to the data buffer for effecting transfer of said blocks of data into and out of said data buffer in said plurality of independent data transfers in a plurality of successions of transfers of blocks of data and adapted to be connected to data source-sinks for transferring such blocks of data with any connected data source-sinks;
• the improvement including, in combination:
• buffer record table means connected to said data buffer and to said transfer means for storing indications of data stored and the available data storage registers for each of said data storage segments;
• system means coupled to said transfer means for counting the number of successions of blocks of data being transferred with a first one of said source-sink means and said data buffer by all of said independent data transfers;
• value means storing and indicating a predetermined count;
• compare means connected to said system means and to said value means for determining and indicating when said count equals or exceeds said predetermined count;
• CCR generating means connected to said buffer record table means and to said transfer means for indicating a system check point when an ensuing transfer of a block of data with a one of said data storage segments cannot be successfully completed;
• CCR counting means connected to said CCR generating means for separately counting each said indicated unsuccessful ensuing transfer of a block of data;
• checking means connected to said compare means, said CCR counting means and to said buffer record table means for responding to said compare means indicating said system check point for accessing the stored indications of said buffer record table means and said separate CCR counts for identifying a one of said data storage segments storing given blocks of data which relate to a one of said independent data transfers having allocation of a data storage segment with a largest one of said CCR counts for allocating an additional data storage segnt to said one independent data transfer;
• allocation control means connected to said checking means, to said buffer record table means and to said data buffer to allocate an additional data storage segment to said one independent data transfer;
• and
• reset means coupled to said CCR counting means and to said checking means for resetting said CCR counts each time said checking means responds to said compare means.

In a data storage system for conducting a plurality of independent data transfers wherein each of said data transfers includes transferring blocks of data in a predetermined succession of such blocks of data;

• a data buffer having a plurality of allocatable data storage segments, each of said segments having a plurality of registers for storing one or more of said blocks of data;
• transfers means coupled to the data buffer for effecting transfer of said blocks of data into and out of said data buffer in said plurality of independent data transfers and adapted to be connected to data source-sinks for transferring such blocks of data with any connected data source-sinks;
• the improvement, including, in combination:
• buffer record table means connected to said data buffer and to said transfer means for storing indications of data stored and available data storage registers for each of said data storage segments;
• system means connected to said transfer means for measuring elapsed time of all data transfers in said transfer means and averaging the measured elapsed times for indicating a normalized predetermined elapsed time;
• checking means connected to said system means and to said buffer record table means for responding to said system means indicating a normalized predetermined elapsed time for accessing the stored indications of said buffer record table means having identifying means for identifying a one of said data storage segments storing given blocks of data and which has predetermined available data storage registers and which relate to a one of said independent data transfers for allocating an additional data storage segment to said one independent data transfer;
• and
• allocation control means connected to said checking means, to said buffer record table means and to said data buffer to allocate an additional data storage segment for said one independent data transfer.

In a data storage system having a data buffer with allocatable data storage segments, each of said data storage segments having a plurality of addressable data storage registers for storing data, means in said data buffer for addressing said addressable registers and said data storage segments, data transfer means in said data buffer for transferring data into and out of said data buffer;

• the improvement including, in combination:
• a programmable digital processor connected to said addressing means, to said data transfer means and to said data buffer for operating same by addressing the data buffer via said addressing means and for supplying command signals to said data buffer for causing the data buffer to receive and supply data respectively for storage and retrieval from addressed ones of said data storage segments;
• a control store connected to said programmable digital processor for storing program indicia to enable said digital processor to operate said data buffer including controlling transfer of data into and out of said data buffer;
• data transfer program indicia in said control store for enabling said digital processor to allocate ones of said data storage segments to respective ones of a plurality of independent series of data transfers such that each of said series of data transfers result in storage and retrieval of data in and from only one of said data storage segments, each said series of data transfers including transferring blocks of data in time separated data transfers;
• buffer record table indicia in said control store for receiving and storing data buffer status signals generated by the programmable digital processor as enabled by said data transfer program indicia and including identification of said stored blocks of data, the amount of data stored in each of said data storage segments;
• counter program indicia in said control store for enabling said digital processor to count the number of times and store the count that a series of data transfers occurs in the data buffer independently of which of said data storage segments stores or retrieves stored data in each said series of data transfers;
• delay count program indicia in said control store for enabling said digital processor to separately count for each of said data storage segments the number of times said data buffer cannot successfully permit a one of said series of data transfers to occur;
• checking program indicia in said control store for enabling said digital processor to respond to said counter program indicia counting to a predetermined value to examine the delay counts as enabled by said delay count program indicia and to select a one of said data storage segments having the largest delay count which represents a one of said independent series of data transfers exhibiting data transfer activity resulting in a maximal data transfer delay;
• allocation program indicia in said control store for enabling said digital processor to allocate an additional one of said data storage segments to said one independent series of data transfers;
• and
• reset program indicia in said control store for enabling said digital processor to reset all of said delay counts and said stored transfer counts each time said checking program indicia has enabled said digital processor to select a one of said data storage segments.

In a machine-implemented method of operating a data buffer having a plurality of allocatable data storage segments;

• including the steps of:
• allocating predetermined ones of said data storage segments for respective independent data transfers;
• transferring data by said independent data transfers in blocks of data;
• measuring the length of blocks of data being transferred in said respective independent data transfers;
• memorizing the amount of data stored and the free space available for data storage in each of said data storage segments as data storage status;
• respectively counting the number of data transfer delays encountered with said independent data transfers as caused by data buffer segment status respectively for data stored in the data buffer and the free data storage space in the respective data storage segments when not meeting the data storage requirements of any given data transfer;
• establishing a normalized time period related to the activity of said data buffer for all of said independent data transfers;
• measuring elapsed time in a normalized manner;
• comparing said measured time with said established time period, when said measured time is less than said established time continue transferring data but when said measured time exceeds or equals said established time, then comparing for each of said data storage segments the number of delays counted and for the data storage segment having the greatest number of said delays counted allocating an additional one of said data storage segment for the independent data transfer having allocation of said data storage segment with said greatest number of delays.

In a method for operation a data storage device having allocatable data storage segments, the steps of:

• establishing a normalized elapsed time measurement period of time related to the total data storage activity of the data storage device such that the busier the data storage device the shorter the normalized elapsed measurement period;
• during each normalized elapsed time measurement period metering the intensity of data transfer activity for each of said data storage segments and keeping a list of data storage segments not having any activity at all;
• allocating ones of said data storage segments for respective ones of a plurality of data transfer operations;
• including deallocating some of the allocated data storage segments and reallocating such deallocated data storage segments for use with other ones of said data transfer operations, during said allocation and deallocation memorizing any contentions for allocated ones of said data storage segments;
• upon expiration of each normalized elapsed time measurement period checking the metered data transfer activities and selecting the data storage segment having the most intense data transfer activity to have an additional one of said data storage segments for its data transfer operations so that said its data transfer operation employs one more of said data storage segments;
• and
• whenever said contention indication is active at the expiration of said normalized elapsed time measurement period, extending said normalized elapsed time measurement period until said contention indication becomes inactive and then perform said checking and electing step.