Hi, I am using swap_notify now. However I have noticed that although the ComprDataSize shrinks as swap is freed, the MemUsedTotal stays relatively high. Presumably this is caused by the swap being freed from effectively random locations in memory, meaning that most of the allocated pages cannot be freed.
Does this suggest that defragmenting the memory allocated by comp-cache may be worthwhile in some circumstances? After doing an interrupted swap off the ratio became even worse. Although compcache managed to free some memory, memory fragmentation rose to 66%. FYI, here are all the relevant stats below. Previously 1GB of swap was used. Also note that 750MB of memory is currently free, so in this case there is no short term benefit to be gained from defragmenting the memory allocated by compcache. ---- After closing some windows, my swap usage dropped from 1GB to 411MB, but MemUsedTotal remained high. x...@xp-desktop:/mnt/big/xp/images/share/Ubuntu904/keytest$ rzstats BackingSwap: /old/swap_4.dd DiskSize: 4194304 kB MemLimit: 1000000 kB NumReads: 1408562 NumWrites: 1047863 FailedReads: 0 FailedWrites: 0 InvalidIO: 0 NotifyFree: 814586 PagesDiscard: 0 ZeroPages: 14374 GoodCompress: 100 % NoCompress: 0 % PagesStored: 102777 PagesUsed: 41309 OrigDataSize: 411108 kB ComprDataSize: 91324 kB MemUsedTotal: 165236 kB BDevNumReads: 171419 BDevNumWrites: 113780 x...@xp-desktop:/mnt/big/xp/images/share/Ubuntu904/keytest$ cat /proc/meminfo MemTotal: 3926280 kB MemFree: 746780 kB Buffers: 59964 kB Cached: 839612 kB SwapCached: 67460 kB Active: 961052 kB Inactive: 724740 kB Active(anon): 564264 kB Inactive(anon): 226532 kB Active(file): 396788 kB Inactive(file): 498208 kB Unevictable: 16 kB Mlocked: 16 kB SwapTotal: 6756624 kB SwapFree: 6294740 kB Dirty: 184 kB Writeback: 0 kB AnonPages: 764088 kB Mapped: 632852 kB Slab: 121576 kB SReclaimable: 90672 kB SUnreclaim: 30904 kB PageTables: 34272 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 8719764 kB Committed_AS: 2589344 kB VmallocTotal: 34359738367 kB VmallocUsed: 80404 kB VmallocChunk: 34359654343 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB DirectMap4k: 3806144 kB DirectMap2M: 387072 kB -- After doing a swapoff, and interruping it, almost half the memory was freed, but memory fragmentation ratio rose to 66% x...@xp-desktop:/mnt/big/xp/images/share/Ubuntu904/keytest$ rzstats BackingSwap: /old/swap_4.dd DiskSize: 4194304 kB MemLimit: 1000000 kB NumReads: 1466336 NumWrites: 1047863 FailedReads: 0 FailedWrites: 0 InvalidIO: 0 NotifyFree: 875438 PagesDiscard: 0 ZeroPages: 14374 GoodCompress: 100 % NoCompress: 0 % PagesStored: 41925 PagesUsed: 22792 OrigDataSize: 167700 kB ComprDataSize: 33310 kB MemUsedTotal: 91168 kB BDevNumReads: 175369 BDevNumWrites: 113780 x...@xp-desktop:/mnt/big/xp/images/share/Ubuntu904/keytest$ cat /proc/meminfo MemTotal: 3926280 kB MemFree: 443012 kB Buffers: 62972 kB Cached: 872620 kB SwapCached: 48956 kB Active: 1055912 kB Inactive: 964876 kB Active(anon): 652512 kB Inactive(anon): 443684 kB Active(file): 403400 kB Inactive(file): 521192 kB Unevictable: 16 kB Mlocked: 16 kB SwapTotal: 6756624 kB SwapFree: 6560424 kB Dirty: 100 kB Writeback: 0 kB AnonPages: 1071652 kB Mapped: 733832 kB Slab: 122624 kB SReclaimable: 91676 kB SUnreclaim: 30948 kB PageTables: 35280 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 8719764 kB Committed_AS: 2684328 kB VmallocTotal: 34359738367 kB VmallocUsed: 80404 kB VmallocChunk: 34359654343 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB DirectMap4k: 3806144 kB DirectMap2M: 387072 kB -- John C. McCabe-Dansted
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