Redis' model is particularly vulnerable to the disk slowdown because the pagefault blocks all requests..
Normally being single-threaded isn't a big deal for Redis because you are likely bound by Network i/o or CPU but using ssd swap is equivalent to using blocking sync disk i/o, which nobody would do :D
Could there be more aggressive memory allocation (basically a region per key / implement moving whole keys to new regions when their ds outgrows the block)? Sure.. but you're still going to pay dearly for the cost of a miss. This approach would help if you want to have only your 'active' ds in memory and let the OS page out cold keys, but this would require major re-work of redis internals (or I thought it would 6 months ago when I last considered this as a fun project..)
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As antirez knows, but others may not:
Redis' model is particularly vulnerable to the disk slowdown because the pagefault blocks all requests..
Normally being single-threaded isn't a big deal for Redis because you are likely bound by Network i/o or CPU but using ssd swap is equivalent to using blocking sync disk i/o, which nobody would do :D
Could there be more aggressive memory allocation (basically a region per key / implement moving whole keys to new regions when their ds outgrows the block)? Sure.. but you're still going to pay dearly for the cost of a miss. This approach would help if you want to have only your 'active' ds in memory and let the OS page out cold keys, but this would require major re-work of redis internals (or I thought it would 6 months ago when I last considered this as a fun project..)