We demonstrate that general-purpose memory allocation involving many threads on many cores can be done with high performance, multicore scalability, and low memory consumption. For this purpose, we have designed and implemented scalloc, a concurrent
allocator that generally performs and scales in our experiments better than other allocators while using less memory, and is still competitive otherwise. The main ideas behind the design of scalloc are: uniform treatment of small and big objects through so-called virtual spans, efficiently and effectively reclaiming free memory through fast and scalable global data structures, and constant-time (modulo synchronization) allocation and deallocation operations that trade off memory reuse and spatial locality without being subject to false sharing.
We study, formally and experimentally, the trade-off in temporal and spatial overhead when managing contiguous blocks of memory using the explicit, dynamic and real-time heap management system Compact-fit (CF). The key property of CF is that temporal
and spatial overhead can be bounded, related, and predicted in constant time through the notion of partial and incremental compaction. Partial compaction determines the maximally tolerated degree of memory fragmentation. Incremental compaction of objects, introduced here, determines the maximal amount of memory involved in any, logically atomic, portion of a compaction operation. We explore CFs potential application space on (1) multiprocessor and multicore systems as well as on (2) memory-constrained uniprocessor systems. For (1), we argue that little or no compaction is likely to avoid the worst case in temporal as well as spatial overhead but also observe that scalability only improves by a constant factor. Scalability can be further improved significantly by reducing overall data sharing through separate instances of Compact-fit. For (2), we observe that incremental compaction can effectively trade-off throughput and memory fragmentation for lower latency.
We present results of a timing analysis of various isolated pulsars using ESAs emph{XMM-Newton} observatory. Isolated pulsars are useful for calibration purposes because of their stable emission. We have analyzed six pulsars with different pulse prof
iles in a range of periods between 15 and 200 ms. All observations were made using the emph{EPIC-pn camera} in its faster modes (Small window, Timing and Burst modes). We investigate the relative timing accuracy of the camera by comparing the pulse periods determined from the emph{EPIC-pn camera} observations with those from radio observations. As a result of our analysis we conclude that the relative timing accuracy of the emph{EPIC-pn camera} is of the order of $1times 10^{-8}$.
