Hi Huge, On 6/6/2023 10:41 AM, Hugh Dickins wrote: > On Mon, 5 Jun 2023, Liam R. Howlett wrote: >> >> You mean "mm: update validate_mm() to use vma iterator" here I guess. I >> have it as a different commit id in my branch. >> >> I 'restored' some of the checking because I was able to work around not >> having the mt_dump() definition with the vma iterator. I'm now >> wondering how wide spread CONFIG_DEBUG_VM is used and if I should not >> have added these extra checks. > > Most CONFIG_DEBUG_VM checks are quite cheap, mostly VM_BUG_ONs for Indeed. I had CONFIG_DEBUG_VM enabled and didn't see surprise perf report. > easily checked conditions. If validate_mm() is still the kind of thing > it used to be, checking through every vma on every mmap operation, please > don't bring that into CONFIG_DEBUG_VM - it distorts performance too much, > so always used to be under a separate CONFIG_DEBUG_VM_RB instead. So does this mean CONFIG_DEBUG_VM is allowed to be enabled for performance testing? Thanks. Regards Yin, Fengwei > > Hugh
