Re: MADV_HUGEPAGE vs. NUMA semantic (was: Re: [LKP] [mm] ac5b2c1891: vm-scalability.throughput -61.3% regression)

2018-12-07 Thread David Rientjes
On Fri, 7 Dec 2018, Vlastimil Babka wrote: > >> But *that* in turn makes for other possible questions: > >> > >> - if the reason we couldn't get a local hugepage is that we're simply > >> out of local memory (huge *or* small), then maybe a remote hugepage is > >> better. > >> > >>Note that

Re: MADV_HUGEPAGE vs. NUMA semantic (was: Re: [LKP] [mm] ac5b2c1891: vm-scalability.throughput -61.3% regression)

2018-12-07 Thread Vlastimil Babka
On 12/7/18 8:49 AM, Michal Hocko wrote: >> But *that* in turn makes for other possible questions: >> >> - if the reason we couldn't get a local hugepage is that we're simply >> out of local memory (huge *or* small), then maybe a remote hugepage is >> better. >> >>Note that this now implies

Re: MADV_HUGEPAGE vs. NUMA semantic (was: Re: [LKP] [mm] ac5b2c1891: vm-scalability.throughput -61.3% regression)

2018-12-06 Thread Michal Hocko
On Thu 06-12-18 20:31:46, Linus Torvalds wrote: > [ Oops. different thread for me due to edited subject, so I saw this > after replying to the earlier email by David ] Sorry about that but I really wanted to make the actual discussion about semantic clearly distinguished because the thread just

Re: MADV_HUGEPAGE vs. NUMA semantic (was: Re: [LKP] [mm] ac5b2c1891: vm-scalability.throughput -61.3% regression)

2018-12-06 Thread Michal Hocko
On Thu 06-12-18 15:49:04, David Rientjes wrote: > On Thu, 6 Dec 2018, Michal Hocko wrote: > > > MADV_HUGEPAGE changes the picture because the caller expressed a need > > for THP and is willing to go extra mile to get it. That involves > > allocation latency and as of now also a potential remote

Re: MADV_HUGEPAGE vs. NUMA semantic (was: Re: [LKP] [mm] ac5b2c1891: vm-scalability.throughput -61.3% regression)

2018-12-06 Thread Linus Torvalds
[ Oops. different thread for me due to edited subject, so I saw this after replying to the earlier email by David ] On Thu, Dec 6, 2018 at 1:14 AM Michal Hocko wrote: > > MADV_HUGEPAGE changes the picture because the caller expressed a need > for THP and is willing to go extra mile to get it.

Re: MADV_HUGEPAGE vs. NUMA semantic (was: Re: [LKP] [mm] ac5b2c1891: vm-scalability.throughput -61.3% regression)

2018-12-06 Thread David Rientjes
On Thu, 6 Dec 2018, Michal Hocko wrote: > MADV_HUGEPAGE changes the picture because the caller expressed a need > for THP and is willing to go extra mile to get it. That involves > allocation latency and as of now also a potential remote access. We do > not have complete agreement on the later

MADV_HUGEPAGE vs. NUMA semantic (was: Re: [LKP] [mm] ac5b2c1891: vm-scalability.throughput -61.3% regression)

2018-12-06 Thread Michal Hocko
On Wed 05-12-18 16:58:02, Linus Torvalds wrote: [...] > I realize that we probably do want to just have explicit policies that > do not exist right now, but what are (a) sane defaults, and (b) sane > policies? I would focus on the current default first (which is defrag=madvise). This means that