diff options
author | Yu Ma | 2023-07-12 10:57:39 -0400 |
---|---|---|
committer | Andrew Morton | 2023-08-18 10:12:26 -0700 |
commit | 6852c46c783d20a4c0153d14d2990040e5e6e47e (patch) | |
tree | 4716a63b046da2fbf02f60ee55111cc95e6a378d /mm/mmap.c | |
parent | 73e791d73877e90444afb6036d86ea37fd78584f (diff) |
mm/mmap: move vma operations to mm_struct out of the critical section of file mapping lock
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 v6.5-rc1 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/
Link: https://lkml.kernel.org/r/20230712145739.604215-1-yu.ma@intel.com
Signed-off-by: Yu Ma <yu.ma@intel.com>
Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Kirill A . Shutemov <kirill@shutemov.name>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Zhu, Lipeng <lipeng.zhu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/mmap.c')
-rw-r--r-- | mm/mmap.c | 11 |
1 files changed, 3 insertions, 8 deletions
diff --git a/mm/mmap.c b/mm/mmap.c index 3937479d0e07..e1586b2f938e 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -412,14 +412,11 @@ static int vma_link(struct mm_struct *mm, struct vm_area_struct *vma) if (vma_iter_prealloc(&vmi)) return -ENOMEM; + vma_iter_store(&vmi, vma); + if (vma->vm_file) { mapping = vma->vm_file->f_mapping; i_mmap_lock_write(mapping); - } - - vma_iter_store(&vmi, vma); - - if (mapping) { __vma_link_file(vma, mapping); i_mmap_unlock_write(mapping); } @@ -2812,12 +2809,10 @@ cannot_expand: /* Lock the VMA since it is modified after insertion into VMA tree */ vma_start_write(vma); - if (vma->vm_file) - i_mmap_lock_write(vma->vm_file->f_mapping); - vma_iter_store(&vmi, vma); mm->map_count++; if (vma->vm_file) { + i_mmap_lock_write(vma->vm_file->f_mapping); if (vma->vm_flags & VM_SHARED) mapping_allow_writable(vma->vm_file->f_mapping); |