| Message ID | a24bf353-8715-2bee-d0fa-96ca06c5b69f@virtuozzo.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/2] mm: use kvzalloc for swap_info_struct allocation | expand |
Vasily Averin <vvs@virtuozzo.com> writes: > Currently newly allocated swap_info_struct can be quickly freed. > This patch avoid uneccessary high-order page allocation and helps > to decrease the memory pressure. I think swapon/swapoff are rare operations, so it will not increase the memory pressure much. Best Regards, Huang, Ying > Signed-off-by: Vasily Averin <vvs@virtuozzo.com> > --- > mm/swapfile.c | 18 +++++++++++++----- > 1 file changed, 13 insertions(+), 5 deletions(-) > > diff --git a/mm/swapfile.c b/mm/swapfile.c > index 8688ae65ef58..53ec2f0cdf26 100644 > --- a/mm/swapfile.c > +++ b/mm/swapfile.c > @@ -2809,14 +2809,17 @@ late_initcall(max_swapfiles_check); > > static struct swap_info_struct *alloc_swap_info(void) > { > - struct swap_info_struct *p; > + struct swap_info_struct *p = NULL; > unsigned int type; > int i; > + bool force_alloc = false; > > - p = kvzalloc(sizeof(*p), GFP_KERNEL); > - if (!p) > - return ERR_PTR(-ENOMEM); > - > +retry: > + if (force_alloc) { > + p = kvzalloc(sizeof(*p), GFP_KERNEL); > + if (!p) > + return ERR_PTR(-ENOMEM); > + } > spin_lock(&swap_lock); > for (type = 0; type < nr_swapfiles; type++) { > if (!(swap_info[type]->flags & SWP_USED)) > @@ -2828,6 +2831,11 @@ static struct swap_info_struct *alloc_swap_info(void) > return ERR_PTR(-EPERM); > } > if (type >= nr_swapfiles) { > + if (!force_alloc) { > + force_alloc = true; > + spin_unlock(&swap_lock); > + goto retry; > + } > p->type = type; > swap_info[type] = p; > /*
On 11/5/18 3:57 AM, Huang, Ying wrote: > Vasily Averin <vvs@virtuozzo.com> writes: > >> Currently newly allocated swap_info_struct can be quickly freed. >> This patch avoid uneccessary high-order page allocation and helps >> to decrease the memory pressure. > > I think swapon/swapoff are rare operations, so it will not increase the > memory pressure much. You are right, typically it should not affect usual nodes. It's OpenVz-specific usecase. OpenVz allows hosters to run hundreds of non-trusted containers per node. Our containers have enabled "virtual swap" functionality, and container's owners can call sys_swapon without any limits. Containers can be restarted in any time and we would like to decrease number of unnecessary high-order memory allocations. >> Signed-off-by: Vasily Averin <vvs@virtuozzo.com> >> --- >> mm/swapfile.c | 18 +++++++++++++----- >> 1 file changed, 13 insertions(+), 5 deletions(-) >> >> diff --git a/mm/swapfile.c b/mm/swapfile.c >> index 8688ae65ef58..53ec2f0cdf26 100644 >> --- a/mm/swapfile.c >> +++ b/mm/swapfile.c >> @@ -2809,14 +2809,17 @@ late_initcall(max_swapfiles_check); >> >> static struct swap_info_struct *alloc_swap_info(void) >> { >> - struct swap_info_struct *p; >> + struct swap_info_struct *p = NULL; >> unsigned int type; >> int i; >> + bool force_alloc = false; >> >> - p = kvzalloc(sizeof(*p), GFP_KERNEL); >> - if (!p) >> - return ERR_PTR(-ENOMEM); >> - >> +retry: >> + if (force_alloc) { >> + p = kvzalloc(sizeof(*p), GFP_KERNEL); >> + if (!p) >> + return ERR_PTR(-ENOMEM); >> + } >> spin_lock(&swap_lock); >> for (type = 0; type < nr_swapfiles; type++) { >> if (!(swap_info[type]->flags & SWP_USED)) >> @@ -2828,6 +2831,11 @@ static struct swap_info_struct *alloc_swap_info(void) >> return ERR_PTR(-EPERM); >> } >> if (type >= nr_swapfiles) { >> + if (!force_alloc) { >> + force_alloc = true; >> + spin_unlock(&swap_lock); >> + goto retry; >> + } >> p->type = type; >> swap_info[type] = p; >> /* >
I was wrong, openVz blocks sys_swapon/swapoff syscalls inside containers. Our kernel just emulates /proc/swaps output inside containers, it is enough for 'swapon' userspace to do not fail and show required info. So I do not have any special arguments for proposed patch. On 11/5/18 8:19 AM, Vasily Averin wrote: > On 11/5/18 3:57 AM, Huang, Ying wrote: >> Vasily Averin <vvs@virtuozzo.com> writes: >> >>> Currently newly allocated swap_info_struct can be quickly freed. >>> This patch avoid uneccessary high-order page allocation and helps >>> to decrease the memory pressure. >> >> I think swapon/swapoff are rare operations, so it will not increase the >> memory pressure much. > > You are right, typically it should not affect usual nodes. > > It's OpenVz-specific usecase. > > OpenVz allows hosters to run hundreds of non-trusted containers per node. > Our containers have enabled "virtual swap" functionality, > and container's owners can call sys_swapon without any limits. > Containers can be restarted in any time and we would like to > decrease number of unnecessary high-order memory allocations. > >>> Signed-off-by: Vasily Averin <vvs@virtuozzo.com> >>> --- >>> mm/swapfile.c | 18 +++++++++++++----- >>> 1 file changed, 13 insertions(+), 5 deletions(-) >>> >>> diff --git a/mm/swapfile.c b/mm/swapfile.c >>> index 8688ae65ef58..53ec2f0cdf26 100644 >>> --- a/mm/swapfile.c >>> +++ b/mm/swapfile.c >>> @@ -2809,14 +2809,17 @@ late_initcall(max_swapfiles_check); >>> >>> static struct swap_info_struct *alloc_swap_info(void) >>> { >>> - struct swap_info_struct *p; >>> + struct swap_info_struct *p = NULL; >>> unsigned int type; >>> int i; >>> + bool force_alloc = false; >>> >>> - p = kvzalloc(sizeof(*p), GFP_KERNEL); >>> - if (!p) >>> - return ERR_PTR(-ENOMEM); >>> - >>> +retry: >>> + if (force_alloc) { >>> + p = kvzalloc(sizeof(*p), GFP_KERNEL); >>> + if (!p) >>> + return ERR_PTR(-ENOMEM); >>> + } >>> spin_lock(&swap_lock); >>> for (type = 0; type < nr_swapfiles; type++) { >>> if (!(swap_info[type]->flags & SWP_USED)) >>> @@ -2828,6 +2831,11 @@ static struct swap_info_struct *alloc_swap_info(void) >>> return ERR_PTR(-EPERM); >>> } >>> if (type >= nr_swapfiles) { >>> + if (!force_alloc) { >>> + force_alloc = true; >>> + spin_unlock(&swap_lock); >>> + goto retry; >>> + } >>> p->type = type; >>> swap_info[type] = p; >>> /* >>
diff --git a/mm/swapfile.c b/mm/swapfile.c index 8688ae65ef58..53ec2f0cdf26 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -2809,14 +2809,17 @@ late_initcall(max_swapfiles_check); static struct swap_info_struct *alloc_swap_info(void) { - struct swap_info_struct *p; + struct swap_info_struct *p = NULL; unsigned int type; int i; + bool force_alloc = false; - p = kvzalloc(sizeof(*p), GFP_KERNEL); - if (!p) - return ERR_PTR(-ENOMEM); - +retry: + if (force_alloc) { + p = kvzalloc(sizeof(*p), GFP_KERNEL); + if (!p) + return ERR_PTR(-ENOMEM); + } spin_lock(&swap_lock); for (type = 0; type < nr_swapfiles; type++) { if (!(swap_info[type]->flags & SWP_USED)) @@ -2828,6 +2831,11 @@ static struct swap_info_struct *alloc_swap_info(void) return ERR_PTR(-EPERM); } if (type >= nr_swapfiles) { + if (!force_alloc) { + force_alloc = true; + spin_unlock(&swap_lock); + goto retry; + } p->type = type; swap_info[type] = p; /*
Currently newly allocated swap_info_struct can be quickly freed. This patch avoid uneccessary high-order page allocation and helps to decrease the memory pressure. Signed-off-by: Vasily Averin <vvs@virtuozzo.com> --- mm/swapfile.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-)