Re: [v5] powerpc/topology: Get topology for shared processors at boot
From: Srikar Dronamraju <hidden>
Date: 2018-08-22 02:05:51
* Michael Ellerman [off-list ref] [2018-08-21 20:35:23]:
On Fri, 2018-08-17 at 14:54:39 UTC, Srikar Dronamraju wrote:quoted
On a shared lpar, Phyp will not update the cpu associativity at boot time. Just after the boot system does recognize itself as a shared lpar and trigger a request for correct cpu associativity. But by then the scheduler would have already created/destroyed its sched domains. This causes - Broken load balance across Nodes causing islands of cores. - Performance degradation esp if the system is lightly loaded - dmesg to wrongly report all cpus to be in Node 0. - Messages in dmesg saying borken topology. - With commit 051f3ca02e46 ("sched/topology: Introduce NUMA identity node sched domain"), can cause rcu stalls at boot up. Previous attempt to solve this problem https://patchwork.ozlabs.org/patch/530090/ Reported-by: Manjunatha H R <redacted> Signed-off-by: Srikar Dronamraju <redacted>Applied to powerpc next, thanks. https://git.kernel.org/powerpc/c/2ea62630681027c455117aa471ea3a
Once it gets to Linus's tree, can we request this to be included in stable trees? -- Thanks and Regards Srikar Dronamraju