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one does not typically find that applications are limited by user-kernel context switches. the OS isn't the bottleneck. Curious, then why are we seeing articl
by dsp1234 11y ago
one does not typically find that applications are limited by user-kernel context switches.
the OS isn't the bottleneck.
Curious, then why are we seeing articles here all the time on bypassing the linux kernel for low latency networking?
- Twirrim 11y agoJust curious, how does a unikernel solve network latency?
- masklinn 11y agoThe issue GP talks about comes from the cost of context-switching on a syscall (going into "kernel mode", performing the call, then going back into "application mode"). There's no context switch in a unikernel.
- BrainInAJar 11y agoWell, unless you count the hypervisor context switch, which you do.
- silly1 11y agoAre you assuming SRV-IOV passthrough (which has its own performance profile) ? Because normal virt -definitely- hits a context switch when it goes from unikernels virtual NIC to real NIC, if not twice.
- shin_lao 11y agoYou don't bypass the kernel, you bypass the TCP stack of the kernel and this is for very specific applications.
- elihu 11y agoBypassing the kernel entirely is pretty normal in HPC applications. Infiniband implementations typically memory-map the device's registers into user-space so that applications can send and receive messages without a system call.
- shin_lao 11y agoThis is not bypassing a kernel. This is called Remote Direct Memory Access (RDMA) and there is still a kernel. FYI most of the devices inside your computer work through DMA.
- EvanPlaice 11y agoOn in particular is network capturing via libpcap. It's basically an alternative driver that comes with additional capabilities. Such as capturing promiscuously, and filtering captures.