Including a dmesg would be helpful here. My guess is you have a CPU with 4 performance/smt cores and 8 efficient cores. Setting hw.blockcpu=E means to block the use of the 8 efficient cores. Setting hw.blockcpu=L means to block lethargic cores, which you have zero of, so the end result is you get access to all 12 cores on your CPU.
It all depends on what you want to achieve. If you don’t mind having processes move between performance and efficient cores, then blocking L or none would be fine. If you want to ensure deterministic processing power, then block E or EL (again, you have no lethargic cores so it doesn’t matter if you include L or not). If your laptop runs fine with hw.blockcpu=L, then use that. Again a dmesg would help us determine what kind of processor you have and therefore how severe the performance degradation is between P and E cores. > On Sep 2, 2026, at 1:20 PM, Ronny Machado <[email protected]> wrote: > > > Okay, this may be a silly question, since 7.9 (which I've been using since > day one) I still don't quite understand the advantages of hw.blockcpu. > > In announcements: > > "Various kernel improvements: > Introduced a mechanism to manage CPU cores with different speeds in the > scheduler. The sysctl(8) variable "hw.blockcpu" takes a sequence of 4 > letters: S (for SMT), P (regular performance CPU), E (efficient CPU, > generally 80% to 50% as fast), and L (lethargic CPU) which are even slower. > Set this to select CPUs to kick out of the scheduler (SL by default). > Currently works on amd64 and arm64." > > Actually I'm running hw.blockcpu=E, and I see 4 cpus, in "L" I see 12...So, > as I said, I still don't quite understand the logic about it, can someone be > so kind to explain that for me? > > In "E" conf, my laptop runs smoothly, VMD and all, in "L" the same... :( > > Thanks in advance > > > -- > > Ronny Machado C. > > > IT Consultant > HP-UX Certified Systems Administrator > Oracle Linux Certified Implementation Specialist > Oracle MySQL Enterprise Certified Implementation Specialist > > https://sysops.cl > +56 9 7519 9262 > > Sent with Proton Mail secure email. >
