> -----Original Message----- > From: Heinrich Schuchardt [mailto:xypron.glpk@xxxxxx] > Sent: Friday, July 03, 2015 10:51 PM > To: Pintu Kumar; corbet@xxxxxxx; akpm@xxxxxxxxxxxxxxxxxxxx; vbabka@xxxxxxx; > gorcunov@xxxxxxxxxx; mhocko@xxxxxxx; emunson@xxxxxxxxxx; > kirill.shutemov@xxxxxxxxxxxxxxx; standby24x7@xxxxxxxxx; > hannes@xxxxxxxxxxx; vdavydov@xxxxxxxxxxxxx; hughd@xxxxxxxxxx; > minchan@xxxxxxxxxx; tj@xxxxxxxxxx; rientjes@xxxxxxxxxx; > dzickus@xxxxxxxxxx; prarit@xxxxxxxxxx; ebiederm@xxxxxxxxxxxx; > rostedt@xxxxxxxxxxx; uobergfe@xxxxxxxxxx; paulmck@xxxxxxxxxxxxxxxxxx; > iamjoonsoo.kim@xxxxxxx; ddstreet@xxxxxxxx; sasha.levin@xxxxxxxxxx; > koct9i@xxxxxxxxx; mgorman@xxxxxxx; cj@xxxxxxxxx; > opensource.ganesh@xxxxxxxxx; vinmenon@xxxxxxxxxxxxxx; linux- > doc@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-mm@xxxxxxxxx; linux- > pm@xxxxxxxxxxxxxxx > Cc: cpgs@xxxxxxxxxxx; pintu_agarwal@xxxxxxxxx; vishnu.ps@xxxxxxxxxxx; > rohit.kr@xxxxxxxxxxx; iqbal.ams@xxxxxxxxxxx > Subject: Re: [PATCH 1/1] kernel/sysctl.c: Add /proc/sys/vm/shrink_memory > feature > > On 03.07.2015 15:20, Pintu Kumar wrote: > > This patch provides 2 things: > > 1. Add new control called shrink_memory in /proc/sys/vm/. > > This control can be used to aggressively reclaim memory system-wide in > > one shot from the user space. A value of 1 will instruct the kernel to > > reclaim as much as totalram_pages in the system. > > Example: echo 1 > /proc/sys/vm/shrink_memory > > > > 2. Enable shrink_all_memory API in kernel with new > CONFIG_SHRINK_MEMORY. > > Currently, shrink_all_memory function is used only during hibernation. > > With the new config we can make use of this API for non-hibernation > > case also without disturbing the hibernation case. > > > > The detailed paper was presented in Embedded Linux Conference, > > Mar-2015 http://events.linuxfoundation.org/sites/events/files/slides/ > > %5BELC-2015%5D-System-wide-Memory-Defragmenter.pdf > > > > Scenarios were this can be used and helpful are: > > 1) Can be invoked just after system boot-up is finished. > > 2) Can be invoked just before entering entire system suspend. > > 3) Can be invoked from kernel when order-4 pages starts failing. > > 4) Can be helpful to completely avoid or delay the kerenl OOM condition. > > 5) Can be developed as a system-tool to quickly defragment entire system > > from user space, without the need to kill any application. > > > > Signed-off-by: Pintu Kumar <pintu.k@xxxxxxxxxxx> > > --- > > Documentation/sysctl/vm.txt | 16 ++++++++++++++++ > > include/linux/swap.h | 7 +++++++ > > kernel/sysctl.c | 9 +++++++++ > > mm/Kconfig | 8 ++++++++ > > mm/vmscan.c | 23 +++++++++++++++++++++-- > > 5 files changed, 61 insertions(+), 2 deletions(-) > > > > diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt > > index 9832ec5..a959ad1 100644 > > --- a/Documentation/sysctl/vm.txt > > +++ b/Documentation/sysctl/vm.txt > > @@ -54,6 +54,7 @@ Currently, these files are in /proc/sys/vm: > > - page-cluster > > - panic_on_oom > > - percpu_pagelist_fraction > > +- shrink_memory > > - stat_interval > > - swappiness > > - user_reserve_kbytes > > @@ -718,6 +719,21 @@ sysctl, it will revert to this default behavior. > > > > ============================================================== > > > > +shrink_memory > > + > > +This control is available only when CONFIG_SHRINK_MEMORY is set. This > > +control can be used to aggressively reclaim memory system-wide in one > > +shot. A value of > > +1 will instruct the kernel to reclaim as much as totalram_pages in the system. > > +For example, to reclaim all memory system-wide we can do: > > +# echo 1 > /proc/sys/vm/shrink_memory > > The API should be as restrictive as possible to allow for extensibility. > > You describe "1" as the only used value. So, please add here: > > "If any other value than 1 is written to shrink_memory an error EINVAL occurs." > Ok, I will handle this error case in next patch set. Actual, I did exactly like compact_memory, so I made this way. > > + > > +For more information about this control, please visit the following > > +presentation in embedded linux conference, 2015. > > +http://events.linuxfoundation.org/sites/events/files/slides/ > > +%5BELC-2015%5D-System-wide-Memory-Defragmenter.pdf > > + > > +============================================================== > > + > > stat_interval > > > > The time interval between which vm statistics are updated. The > > default diff --git a/include/linux/swap.h b/include/linux/swap.h index > > 9a7adfb..6505b0b 100644 > > --- a/include/linux/swap.h > > +++ b/include/linux/swap.h > > @@ -333,6 +333,13 @@ extern int vm_swappiness; extern int > > remove_mapping(struct address_space *mapping, struct page *page); > > extern unsigned long vm_total_pages; > > > > +#ifdef CONFIG_SHRINK_MEMORY > > +extern int sysctl_shrink_memory; > > +extern int sysctl_shrinkmem_handler(struct ctl_table *table, int write, > > + void __user *buffer, size_t *length, loff_t *ppos); #endif > > + > > + > > #ifdef CONFIG_NUMA > > extern int zone_reclaim_mode; > > extern int sysctl_min_unmapped_ratio; diff --git a/kernel/sysctl.c > > b/kernel/sysctl.c index c566b56..2895099 100644 > > --- a/kernel/sysctl.c > > +++ b/kernel/sysctl.c > > @@ -1351,6 +1351,15 @@ static struct ctl_table vm_table[] = { > > }, > > > > #endif /* CONFIG_COMPACTION */ > > +#ifdef CONFIG_SHRINK_MEMORY > > + { > > + .procname = "shrink_memory", > > + .data = &sysctl_shrink_memory, > > + .maxlen = sizeof(int), > > + .mode = 0200, > > + .proc_handler = sysctl_shrinkmem_handler, > > Supply the value limits. > > int min_shrink_memory = 1; > int max_shrink_memory = 1; > > .extra1 = &min_shrink_memory, > .extra2 = &max_shrink_memory, > Ok, I will include this value as well in the new patch set. > > + }, > > +#endif > > { > > .procname = "min_free_kbytes", > > .data = &min_free_kbytes, > > diff --git a/mm/Kconfig b/mm/Kconfig > > index b3a60ee..8e04bd9 100644 > > --- a/mm/Kconfig > > +++ b/mm/Kconfig > > @@ -657,3 +657,11 @@ config DEFERRED_STRUCT_PAGE_INIT > > when kswapd starts. This has a potential performance impact on > > processes running early in the lifetime of the systemm until kswapd > > finishes the initialisation. > > + > > +config SHRINK_MEMORY > > + bool "Allow for system-wide shrinking of memory" > > + default n > > + depends on MMU > > + help > > + It enables support for system-wide memory reclaim in one shot using > > + echo 1 > /proc/sys/vm/shrink_memory. > > diff --git a/mm/vmscan.c b/mm/vmscan.c index c8d8282..837b88d 100644 > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c > > @@ -3557,7 +3557,7 @@ void wakeup_kswapd(struct zone *zone, int order, > enum zone_type classzone_idx) > > wake_up_interruptible(&pgdat->kswapd_wait); > > } > > > > -#ifdef CONFIG_HIBERNATION > > +#if defined CONFIG_HIBERNATION || CONFIG_SHRINK_MEMORY > > /* > > * Try to free `nr_to_reclaim' of memory, system-wide, and return the number > of > > * freed pages. > > @@ -3571,12 +3571,17 @@ unsigned long shrink_all_memory(unsigned long > nr_to_reclaim) > > struct reclaim_state reclaim_state; > > struct scan_control sc = { > > .nr_to_reclaim = nr_to_reclaim, > > +#ifdef CONFIG_SHRINK_MEMORY > > + .gfp_mask = (GFP_HIGHUSER_MOVABLE | GFP_RECLAIM_MASK), > > + .hibernation_mode = 0, > > +#else > > .gfp_mask = GFP_HIGHUSER_MOVABLE, > > + .hibernation_mode = 1, > > +#endif > > .priority = DEF_PRIORITY, > > .may_writepage = 1, > > .may_unmap = 1, > > .may_swap = 1, > > - .hibernation_mode = 1, > > }; > > struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask); > > struct task_struct *p = current; > > @@ -3597,6 +3602,20 @@ unsigned long shrink_all_memory(unsigned long > > nr_to_reclaim) } #endif /* CONFIG_HIBERNATION */ > > > > +#ifdef CONFIG_SHRINK_MEMORY > > +int sysctl_shrink_memory; > > +/* This is the entry point for system-wide shrink memory > > ++via /proc/sys/vm/shrink_memory */ > > +int sysctl_shrinkmem_handler(struct ctl_table *table, int write, > > + void __user *buffer, size_t *length, loff_t *ppos) { > > Check if *buffer contains "1". If the value is not "1" return -EINVAL. > > The check can be done using function proc_dointvec_minmax(). > Ok, I will include this case also in the new patch set. Thanks for the review and suggestions. > Best regards > > Heinrich Schuchardt > > > + if (write) > > + shrink_all_memory(totalram_pages); > > + > > + return 0; > > +} > > +#endif > > + > > /* It's optimal to keep kswapds on the same CPUs as their memory, but > > not required for correctness. So if the last cpu in a node goes > > away, we get changed to run anywhere: as the first one comes back, > > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>