To be precise, each socket has 3 16x line. The others (1x, 2x, 4x, 8x) goes through the PCH before reaching the CPU, as usual. "lspci -tv" to view the pci topology.
On Thursday, May 25, 2017 at 7:58:00 AM UTC+2, Wojciech Kudla wrote: > > > Since Sandy Bridge at least, each CPU has > its own PCIe interface. Presumably, if you're doing user-space kernel > bypass IO you want your workload on the same CPU that your IO devices are > connected to. > > I think you meant the whole socket here. Yes, this is one of the reasons > why many shops move away from 4-socket rigs as it sometimes gets really > challenging to partition PCIe/cpu/memory resources when running multiple > latency critical processes. > > On Thu, 25 May 2017, 00:49 Ross Bencina, <[email protected] > <javascript:>> wrote: > >> On 22/05/2017 5:47 PM, Himanshu Sharma wrote: >> > Did you find a satisfactory reason for not isolating cpu 0, maybe some >> > low level OS code that is bound to run on core 0? >> >> Throwing this out there for comment: >> >> In addition to Linux kernel internals, you might want to consider which >> CPU your IO is connected to. Since Sandy Bridge at least, each CPU has >> its own PCIe interface. Presumably, if you're doing user-space kernel >> bypass IO you want your workload on the same CPU that your IO devices >> are connected to. Otherwise you want the kernel running on the CPU that >> is directly connected to IO. >> >> Or you could work out the CPU isolation first then connect IO as >> appropriate. >> >> Ross. >> >> -- >> You received this message because you are subscribed to the Google Groups >> "mechanical-sympathy" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected] <javascript:>. >> For more options, visit https://groups.google.com/d/optout. >> > -- You received this message because you are subscribed to the Google Groups "mechanical-sympathy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
