Method for reducing memory conflicts caused by busy waiting in multiple processor synchronisation
K. Mühlemann · IEE Proceedings E Computers and Digital Techniques · 1980
To implement synchronisation by process switching for multiple processors, more basic synchronisation means are needed which delay a process by busy waiting. This busy waiting may cause severe memory conflicts as a side effect. A considerable reduction of these memory conflicts can be acheived by testing a lock variable only at those instants when there is a fair chance of finding it unlocked. An effort in this direction was made in the C. mmp design. Certain deficiencies of that approach, mainly related to its use of the interrupt mechanism, are avoided in a new approach which is based on an ‘eavesdropping’ state of the processor. The astonishingly simple solution only requires minor extensions of present-day processor designs.