Messages in this thread |  | | Subject | Re: [PATCH v3 3/5] x86/mm: Optionally flush L1D on context switch | From | "Singh, Balbir" <> | Date | Fri, 4 Dec 2020 22:41:31 +0000 |
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On Fri, 2020-12-04 at 22:21 +0100, Thomas Gleixner wrote: > CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you can confirm the sender and know the content is safe. > > > > On Fri, Nov 27 2020 at 17:59, Balbir Singh wrote: > > > > + /* > > + * Flush only if SMT is disabled as per the contract, which is checked > > + * when the feature is enabled. > > + */ > > + if (sched_smt_active() && !this_cpu_read(cpu_info.smt_active) && > > + (prev_mm & LAST_USER_MM_L1D_FLUSH)) > > + l1d_flush_hw(); > > So if SMT is completely disabled then no flush? Shouldn't the logic be: > > if ((!sched_smt_active() || !this_cpu_read(cpu_info.smt_active) && > (prev_mm & LAST_USER_MM_L1D_FLUSH)) > > Hmm? > > But that's bad, because it's lot's of conditions to evaluate for every > switch_mm where most of them are not interested in it at all. > > Let me read through the rest of the pile. >
We don't need this anymore with the new checks for preempting killing of the task, so it can be removed
Balbir
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