Comments for post On Redis, Memcached, Speed, Benchmarks and The Toilet
jjmaestro writes: First things first: **awesome** article! Kudos!
Next, What happened to speed.redis.io? :) It would be a really cool thing to have.
Cheers!
Steve Crane writes: My last comment was a little premature and I have discovered the comment in the config file that explains how to disable persistence.
Steve Crane writes: I'm investigating how to turn persistence off in Redis; the documentation is not specific about this but I came across this article and wondered if you could tell me how you turned off the persistence? Thanks.
Gleb Peregud writes: Mikhail, I've checked it with rebasing betterparsing branch onto 2.2.2 tag and it shown that changes contianed in the betterparsing are already in 2.2.2 tree. Antirez, please correct me if I'm wrong.
Mikhail Mikheev writes: Antirez,
Does release candidate 2.2 contain the fix of MGET performance you wrote about? As I was not able to find anything about improving MGET performance in release notes for neither release 2.0 nor 2.2
burberry shoes writes: More please, this information helped me consider a few more things, keep up the good work. http://www.watcheshall.com/burberry-shoes.html
Asad writes: Why do you consider memcached and Redis comparison an apple to apple comparison -- memcached has no guarantee that if a set was successful, the next get would return successfully too (even if expiration time is not passed and there is no process restart or network outage). Redis on the other hand must support this (if no expiration + no restart + no network outage) (correct me if I am wrong). Because of this difference memcached can use UDP while Redis can't. For that matter, I wonder if memcached with UDP would be faster than Redis.
Robert writes: Just wanted to say thank you for caring so much about speed, and for creating redis.
To me redis fills a different role than memcached and so comparing the two isn't something that I'm all that interested in.
I'm not using redis yet in any live projects, but I have used it in two projects I was working on developing and am likely to use it in future projects :)
obs writes: I like the idea of speed.redis.io it'll be interesting to see the performance of redis change as features are added.
brianthecoder writes: @Julien my guess is you don't have persistence turned off like @antirez does since that's not the default
Keytweetlouie writes: I agree with you that lightning fast speed is important before horizontal scaling. My guess would be people shard before they have truly optimized all of their code.
Effie writes: http://en.oreilly.com/velocity2010/public/schedule/detail/13046 outlines a methodology to actually quantify scalability as shown with memcached and outlines problems in that software. Have a look and see if that would be useful as an approach...
WolfHumble writes: Semantics -- you saw it coming ;-)
> if [ $(($S > $SPEED)) != "0" ]
If "S" is always a whole number (looks like that from the cut part) I think I would have gone for either:
if [ $S -ge $SPEED ]
OR
if (($S > $SPEED))
For more, see:
http://tldp.org/LDP/abs/html/comparison-ops.html#ICOMPARISON1
WolfHumble
antirez writes: @Pedro: unlikely to make any difference, with redis-benchmark the numbers are exactly the same. The only difference if you send an MGET with many many keys in the same command.
Pedro Teixeira writes: @Julien: also maybe you are not using the "betterparsing" branch of Redis?
antirez writes: Julien: this is what I get from cat /proc/cpuinfo:
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 23
model name : Intel(R) Core(TM)2 Quad CPU Q8300 @ 2.50GHz
stepping : 10
cpu MHz : 1998.000
cache size : 2048 KB
So it's not so bad actually, but we bought it for 300 euros, so I guess not at the level of a decent Linux server.
About optimizations, it seems like Redis is mostly CPU bound so the faster CPU the better (trying to compile with -O3 can help as well). The other obvious part where it's worth investigating is parallelism and networking stack: network links between DB and web servers and so forth.
Julien writes: What do you call a "oldish Linux box"? I'm asking because I'd love to optimize our various redis instances, and we're not getting the same kind of performance that you get. It would greatly help to have some kind of "ckecklist" on how to have a faster redis.
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