> -----Original Message----- > From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > Sent: Wednesday, July 12, 2023 2:28 AM > To: Ma, Yu <yu.ma@xxxxxxxxx> > Cc: Liam.Howlett@xxxxxxxxxx; kirill@xxxxxxxxxxxxx; Williams, Dan J > <dan.j.williams@xxxxxxxxx>; Hansen, Dave <dave.hansen@xxxxxxxxx>; linux- > kernel@xxxxxxxxxxxxxxx; linux-mm@xxxxxxxxx; Zhu, Lipeng > <lipeng.zhu@xxxxxxxxx>; Deng, Pan <pan.deng@xxxxxxxxx>; > shakeelb@xxxxxxxxxx; Li, Tianyou <tianyou.li@xxxxxxxxx>; Chen, Tim C > <tim.c.chen@xxxxxxxxx>; tim.c.chen@xxxxxxxxxxxxxxx > Subject: Re: [PATCH v2] mm/mmap: move vma operations to mm_struct out > of the critical section of file mapping lock > > On Tue, 11 Jul 2023 13:20:20 -0400 Yu Ma <yu.ma@xxxxxxxxx> wrote: > > > UnixBench/Execl represents a class of workload where bash scripts are > > spawned frequently to do some short jobs. When running multiple > > parallel tasks, hot osq_lock is observed from do_mmap and exit_mmap. > > Both of them come from load_elf_binary through the call chain > > "execl->do_execveat_common->bprm_execve->load_elf_binary". In > > do_mmap,it will call mmap_region to create vma node, initialize it and > > insert it to vma maintain structure in mm_struct and i_mmap tree of > > the mapping file, then increase map_count to record the number of vma > > nodes used. The hot osq_lock is to protect operations on file’s i_mmap > > tree. For the mm_struct member change like vma insertion and map_count > > update, they do not affect i_mmap tree. Move those operations out of > > the lock's critical section, to reduce hold time on the lock. > > > > With this change, on Intel Sapphire Rapids 112C/224T platform, based > > on v6.0-rc6, the 160 parallel score improves by 12%. The patch has no > > obvious performance gain on v6.4-rc4 due to regression of this > > benchmark from this commit f1a7941243c102a44e8847e3b94ff4ff3ec56f25 > > (mm: convert mm's rss stats into percpu_counter). Related discussion > > and conclusion can be referred at the mail thread initiated by 0day as > below: > > Link: > > https://lore.kernel.org/linux-mm/a4aa2e13-7187-600b-c628- > 7e8fb108def0@ > > intel.com/ > > Could you please redo/retest this against a kernel which has > 1c7873e3364 ("mm: lock newly mapped VMA with corrected ordering")? > mainline, mm-unstable or linux-next. > OK, no problem. Regards Yu
