"But i found if i do not set their cpu affinity that is they run on same core 0 the time performance get better than setting cpu affinity 8.76s vs 14.66s"

"Cpu affinity it s better for the cpu to have a load average of 1.0 and processes to have affinity to a single core"

"Also note - if rdtsc is used without an invariant time source on linux grep constant_tsc proc cpuinfo you may get unreliable values across frequency changes and if the task switches cpu time source;so in general yes setting the affinity does gives lower latency but this is not always true and there are very serious costs when you do this"

Use irq affinity to set other cpus to handle all interrupts so that your isolated cpu will not receive any interrupts;use cpu affinity to fix your specific task to the isolated cpu

With a query that doesn t end up blocking on resources on a 4-core machine you theoretically get a 4-times speed up 4 hyper-threaded might give you more or even less but probably not 8-times since hyperthreading s doubling of some parts of the cpu doesn t give a clear two-times increase;with the same query on a single-core or with processors affinity meaning only one core is available a webserver in web-garden mode then there s no speed-up

Cpu is multicore user-space app will have affinity to one core

Further more in deadline scheduling kernel rejects setting when cpu affinity mask is smaller than the entire root_domain in what case would cpu affinity mask become smaller than the root_domain span

The cpu affinity is more like a suggestion to the kernel regarding which cpu to use

So you may be starving ssis of cpu not memory;you could try changing processors affinity to allow sql server to use only 16 cores and let the memory find it s own level