Sorry, correcting a small typo error below. Please review and provide your comments. This is the version2 of the previous patch. > -----Original Message----- > From: Pintu Kumar [mailto:pintu.k@xxxxxxxxxxx] > Sent: Friday, July 17, 2015 12:00 PM > To: akpm@xxxxxxxxxxxxxxxxxxxx; corbet@xxxxxxx; vbabka@xxxxxxx; > gorcunov@xxxxxxxxxx; pintu.k@xxxxxxxxxxx; mhocko@xxxxxxx; > emunson@xxxxxxxxxx; kirill.shutemov@xxxxxxxxxxxxxxx; > standby24x7@xxxxxxxxx; hannes@xxxxxxxxxxx; vdavydov@xxxxxxxxxxxxx; > hughd@xxxxxxxxxx; minchan@xxxxxxxxxx; tj@xxxxxxxxxx; rientjes@xxxxxxxxxx; > xypron.glpk@xxxxxx; 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; qiuxishi@xxxxxxxxxx; Valdis.Kletnieks@xxxxxx > Cc: cpgs@xxxxxxxxxxx; pintu_agarwal@xxxxxxxxx; vishnu.ps@xxxxxxxxxxx; > rohit.kr@xxxxxxxxxxx; iqbal.ams@xxxxxxxxxxx; pintu.ping@xxxxxxxxx; > pintu.k@xxxxxxxxxxx > Subject: [PATCHv2 1/1] kernel/sysctl.c: Add /proc/sys/vm/shrink_memory > feature > > 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 > > If any other value than 1 is written to shrink_memory an error EINVAL occurs. > > 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 > > A sample example is shown below: > Device: ARMv7, Dual Core CPU 1.2GHz > RAM: 512MB (Without SWAP/ZRAM) > Linux Kernel: 3.10.17 > Scenario: Just after boot-up finished. > > BEFORE: > ------------------------------------------------------------------------- > shell> free -tm ; cat /proc/buddyinfo > total used free shared buffers cached > Mem: 460 440 20 0 35 154 > -/+ buffers/cache: 250 209 > Swap: 0 0 0 > Total: 460 440 20 > Node 0, zone Normal 1037 705 92 19 19 17 4 9 0 0 0 > > shell> vmstat 1 & > > AFTER: > ------------------------------------------------------------------------- > shell> echo 1 > /proc/sys/vm/shrink_memory > > r b swpd free buff cache si so bi bo in cs us sy id wa st > 0 0 0 20768 35876 157876 0 0 0 0 64 177 0 1 99 0 0 > -------------------------------------------------------------------------------- > |1 0 0 33104 34864 149808 0 0 0 0 82 221 0 12 88 0 0| > -------------------------------------------------------------------------------- > 0 0 0 188776 3000 54420 0 0 0 0 216 374 0 30 70 0 0 > 0 0 0 188400 3652 54528 0 0 740 8 188 337 2 1 95 2 0 > > shell> free -tm ; cat /proc/buddyinfo > total used free shared buffers cached > Mem: 460 278 182 0 4 54 > -/+ buffers/cache: 219 240 > Swap: 0 0 0 > Total: 460 278 182 > Node 0, zone Normal 5575 3158 1500 727 240 90 33 18 10 6 > 6 > > RESULTS: > ----------------------------------------------------- > Around 160MB of memory were recovered in one shot. > Many higher-order pages were recovered in the process. > From the vmstat output the total CPU usage is: ~12% (system), when this > command is running, for 1 second. > We also measured the power consumption using H/W power monitor tool. > Below is the result: > Before - ~180mA > During shrink memory - ~237mA > Duration - ~0.5 sec > Consumption: ~57mA > > FURTHER OBSERVATIONS: > ----------------------------------------------------- > 37% reduction in killing of application with memory shrink calling on boot up. > Around ~4000 page faults are reduced. > Around ~43% of reduction in kswapd calls. > Movement to slowpath reduced dractically. > Combining shrink_memory with compaction shows good benefits over > fragmentation. > > APPLICATION LAUNCH BEHAVIOR: > ----------------------------------------------------- > During First Launch: > ================================================================== > ========== > Application Before_shrink_memory After_shrink_memory Difference > Camera 1.981 1.86 0.121 > Gallery 1.276 0.94 0.336 > contacts 1.112 0.941 0.171 > messaging 0.886 0.795 0.091 > settings 1.257 1.212 0.045 > Music 1.854 2.098 -0.244 > Gmail 1.872 1.935 -0.063 > Browser 2.569 2.677 -0.108 > ================================================================== > ========== > > During Re-launch: > ================================================================== > ========== > Application Before_shrink_memory After_shrink_memory Difference > Camera 1.248 0.976 0.272 > Gallery 0.697 0.633 0.064 > contacts 0.506 0.561 -0.055 > messaging 0.533 0.489 0.044 > settings 0.833 0.805 0.028 > Music 0.832 0.769 0.063 > Gmail 0.913 0.841 0.072 > Browser 0.579 0.57 0.009 > ================================================================== > ========== > > Various other use cases where this can be used: > ---------------------------------------------------------------------------- > 1) Just after system boot-up is finished, using the sysctl configuration from > bootup script. > 2) During system suspend state, after suspend_freeze_processes() > [kernel/power/suspend.c] > Based on certain condition about fragmentation or free memory state. > 3) From Android ION system heap driver, when order-4 allocation starts failing. > By calling shrink_all_memory, in a separate worker thread, based on certain > condition. > 4) It can be combined with compact_memory to achieve better results on > memory > fragmentation. > 5) It can be helpful in debugging and tuning various vm parameters. > 6) It can be helpful to identify how much of maximum memory could be > reclaimable at any point of time. > And how much higher-order pages could be formed with this amount of > reclaimable memory. > Thus it can be helpful in accordingly tuning the reserved memory needs > of a system. > 7) It can be helpful in properly tuning the SWAP size in the system. > In shrink_all_memory, we enable may_swap = 1, that means all unused pages > will be swapped out. > Thus, running shrink_memory on a heavy loaded system, we can check how > much > swap is getting full. > That can be the maximum swap size with a 10% delta. > Also if ZRAM is used, it helps us in compressing and storing the pages for > later use. > 8) It can be helpful to allow more new applications to be launched, without > killing the older once. > And moving the least recently used pages to the SWAP area. > Thus user data can be retained. > 9) Can be part of a system system-tool to quickly defragment entire system > memory. > 10) This may also help in reducing fragmentation within CMA region. > 11) More use cases can be identified. > > Most importantly, it can be more effective when applied intelligently, based on > certain conditions. > It should be executed always and the decision is left upto the user. * It should _not_ be executed always. The decision is left to the user. > > Signed-off-by: Pintu Kumar <pintu.k@xxxxxxxxxxx> > --- > V2: Added min,max parameter for shrink_memory, suggested by > Heinrich Schuchardt <xypron.glpk@xxxxxx>. > Error handling in sysctl_shrinkmem_handler, for any value other than 1, > suggested by, Heinrich Schuchardt <xypron.glpk@xxxxxx>. > Fixed HIBERNATION+SHRINK_MEMORY issue in shrink_all_memory, > suggested by Valdis.Kletnieks@xxxxxx. > Restore gfp_mask to original, because of other dependencies. > Also adding GFP_RECLAIM_MASK, does not affect anything. > Verified power consumption data during shrink_memory, > as suggested by Johannes Weiner <hannes@xxxxxxxxxxx>. > Verified application launch/re-launch scenarios before/after shrink_memory, > as suggested by Xishi Qiu <qiuxishi@xxxxxxxxxx>. > Updates the commit messages with examples and use cases. > > Documentation/sysctl/vm.txt | 18 ++++++++++++++++++ > include/linux/swap.h | 7 +++++++ > kernel/sysctl.c | 16 ++++++++++++++++ > mm/Kconfig | 8 ++++++++ > mm/vmscan.c | 34 ++++++++++++++++++++++++++++++++-- > 5 files changed, 81 insertions(+), 2 deletions(-) > > diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt index > 9832ec5..54eda3a 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 +719,23 @@ 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 > + > +If any other value than 1 is written to shrink_memory an error EINVAL occurs. > + > +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..e66581b 100644 > --- a/kernel/sysctl.c > +++ b/kernel/sysctl.c > @@ -275,6 +275,11 @@ static int min_extfrag_threshold; static int > max_extfrag_threshold = 1000; #endif > > +#ifdef CONFIG_SHRINK_MEMORY > +static int min_shrink_memory = 1; > +static int max_shrink_memory = 1; > +#endif > + > static struct ctl_table kern_table[] = { > { > .procname = "sched_child_runs_first", > @@ -1351,6 +1356,17 @@ 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, > + .extra1 = &min_shrink_memory, > + .extra2 = &max_shrink_memory, > + }, > +#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..e802fa7 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -58,6 +58,10 @@ > #define CREATE_TRACE_POINTS > #include <trace/events/vmscan.h> > > +#ifdef CONFIG_SHRINK_MEMORY > +#include <linux/suspend.h> > +#endif > + > struct scan_control { > /* How many pages shrink_list() should reclaim */ > unsigned long nr_to_reclaim; > @@ -3557,7 +3561,7 @@ 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. > @@ -3576,12 +3580,16 @@ unsigned long shrink_all_memory(unsigned long > nr_to_reclaim) > .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; > unsigned long nr_reclaimed; > > + if (system_entering_hibernation()) > + sc.hibernation_mode = 1; > + else > + sc.hibernation_mode = 0; > + > p->flags |= PF_MEMALLOC; > lockdep_set_current_reclaim_state(sc.gfp_mask); > reclaim_state.reclaimed_slab = 0; > @@ -3597,6 +3605,28 @@ 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) { > + int ret; > + > + ret = proc_dointvec_minmax(table, write, buffer, length, ppos); > + if (ret) > + return ret; > + > + if (write) { > + if (sysctl_shrink_memory & 1) > + 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, > -- > 1.7.9.5 -- 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>