Messages in this thread Patch in this message | | | Date | Wed, 21 Apr 2010 18:02:48 -0700 | From | Dmitry Torokhov <> | Subject | Re: [Pv-drivers] [PATCH v2] VMware Balloon driver |
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On Wed, Apr 21, 2010 at 05:00:49PM -0700, Dmitry Torokhov wrote: > On Wed, Apr 21, 2010 at 04:54:49PM -0700, Andrew Morton wrote: > > On Thu, 15 Apr 2010 14:00:31 -0700 > > Dmitry Torokhov <dtor@vmware.com> wrote: > > > > > This is standalone version of VMware Balloon driver. Ballooning is a > > > technique that allows hypervisor dynamically limit the amount of memory > > > available to the guest (with guest cooperation). In the overcommit > > > scenario, when hypervisor set detects that it needs to shuffle some memory, > > > it instructs the driver to allocate certain number of pages, and the > > > underlying memory gets returned to the hypervisor. Later hypervisor may > > > return memory to the guest by reattaching memory to the pageframes and > > > instructing the driver to "deflate" balloon. > > > > > > Signed-off-by: Dmitry Torokhov <dtor@vmware.com> > > > --- > > > > > > Unlike previous version, that tried to integrate VMware ballooning transport > > > into virtio subsystem, and use stock virtio_ballon driver, this one implements > > > both controlling thread/algorithm and hypervisor transport. > > > > > > We are submitting standalone driver because KVM maintainer (Avi Kivity) > > > expressed opinion (rightly) that our transport does not fit well into > > > virtqueue paradigm and thus it does not make much sense to integrate > > > with virtio. > > > > > > There were also some concerns whether current ballooning technique is > > > the right thing. If there appears a better framework to achieve this we > > > are prepared to evaluate and switch to using it, but in the meantime > > > we'd like to get this driver upstream. > > > > > > Changes since v1: > > > - added comments throughout the code; > > > - exported stats moved from /proc to debugfs; > > > - better changelog. > > > > > > > > > ... > > > > > > +#define VMW_BALLOON_NOSLEEP_ALLOC_MAX 16384U > > > + > > > +#define VMW_BALLOON_RATE_ALLOC_MIN 512U > > > +#define VMW_BALLOON_RATE_ALLOC_MAX 2048U > > > +#define VMW_BALLOON_RATE_ALLOC_INC 16U > > > + > > > +#define VMW_BALLOON_RATE_FREE_MIN 512U > > > +#define VMW_BALLOON_RATE_FREE_MAX 16384U > > > +#define VMW_BALLOON_RATE_FREE_INC 16U > > > > hum. What do these do and what units are they in? Needs a comment? > > These control inflating/deflating rate of the ballon, mesured in > pages/sec. I will add a comment. > > > > > > > > > ... > > > > > > +#define VMWARE_BALLOON_CMD(cmd, data, result) \ > > > +({ \ > > > + unsigned long __stat, __dummy1, __dummy2; \ > > > + __asm__ __volatile__ ("inl (%%dx)" : \ > > > + "=a"(__stat), \ > > > + "=c"(__dummy1), \ > > > + "=d"(__dummy2), \ > > > + "=b"(result) : \ > > > + "0"(VMW_BALLOON_HV_MAGIC), \ > > > + "1"(VMW_BALLOON_CMD_##cmd), \ > > > + "2"(VMW_BALLOON_HV_PORT), \ > > > + "3"(data) : \ > > > + "memory"); \ > > > + result &= -1UL; \ > > > + __stat & -1UL; \ > > > +}) > > > > This is OK for both x86_32 and x86_64? > > Yes it is. > > > > > Was it actually intended that this driver be enabled for 32-bit? > > > > Yes. > > > > +#define STATS_INC(stat) (stat)++ > > > + > > > +struct vmballoon_stats { > > > + unsigned int timer; > > > + > > > + /* allocation statustics */ > > > + unsigned int alloc; > > > + unsigned int alloc_fail; > > > + unsigned int sleep_alloc; > > > + unsigned int sleep_alloc_fail; > > > + unsigned int refused_alloc; > > > + unsigned int refused_free; > > > + unsigned int free; > > > + > > > + /* monitor operations */ > > > + unsigned int lock; > > > + unsigned int lock_fail; > > > + unsigned int unlock; > > > + unsigned int unlock_fail; > > > + unsigned int target; > > > + unsigned int target_fail; > > > + unsigned int start; > > > + unsigned int start_fail; > > > + unsigned int guest_type; > > > + unsigned int guest_type_fail; > > > +}; > > > + > > > +struct vmballoon { > > > + > > > + /* list of reserved physical pages */ > > > + struct list_head pages; > > > + > > > + /* transient list of non-balloonable pages */ > > > + struct list_head refused_pages; > > > + > > > + /* balloon size in pages */ > > > + unsigned int size; > > > + unsigned int target; > > > + > > > + /* reset flag */ > > > + bool reset_required; > > > + > > > + /* adjustment rates (pages per second) */ > > > + unsigned int rate_alloc; > > > + unsigned int rate_free; > > > + > > > + /* slowdown page allocations for next few cycles */ > > > + unsigned int slow_allocation_cycles; > > > + > > > + /* statistics */ > > > + struct vmballoon_stats stats; > > > + > > > + /* debugfs file exporting statistics */ > > > + struct dentry *dbg_entry; > > > + > > > + struct sysinfo sysinfo; > > > + > > > + struct delayed_work dwork; > > > +}; > > > > afaict all the stats stuff is useless if CONFIG_DEBUG_FS=n. Perhaps in > > that case the vmballoon.stats field should be omitted and STATS_INC > > be made a no-op? > > > > OK, will do. > > Thanks Andrew. >
OK, so here is the incremental patch addressing your comments. Or do you want the entire thing resent?
Thanks.
-- Dmitry
vmware-balloon: miscellaneous fixes
- document rate allocation constants - do not compile statistics code when debugfs is disabled - fix compilation error when debugfs is disabled
Signed-off-by: Dmitry Torokhov <dtor@vmware.com> ---
drivers/misc/vmware_balloon.c | 38 +++++++++++++++++++++++++++++++------- 1 files changed, 31 insertions(+), 7 deletions(-)
diff --git a/drivers/misc/vmware_balloon.c b/drivers/misc/vmware_balloon.c index 90bba04..e7161c4 100644 --- a/drivers/misc/vmware_balloon.c +++ b/drivers/misc/vmware_balloon.c @@ -50,12 +50,28 @@ MODULE_ALIAS("dmi:*:svnVMware*:*"); MODULE_ALIAS("vmware_vmmemctl"); MODULE_LICENSE("GPL"); +/* + * Various constants controlling rate of inflaint/deflating balloon, + * measured in pages. + */ + +/* + * Rate of allocating memory when there is no memory pressure + * (driver performs non-sleeping allocations). + */ #define VMW_BALLOON_NOSLEEP_ALLOC_MAX 16384U +/* + * Rates of memory allocaton when guest experiences memory pressure + * (driver performs sleeping allocations). + */ #define VMW_BALLOON_RATE_ALLOC_MIN 512U #define VMW_BALLOON_RATE_ALLOC_MAX 2048U #define VMW_BALLOON_RATE_ALLOC_INC 16U +/* + * Rates for releasing pages while deflating balloon. + */ #define VMW_BALLOON_RATE_FREE_MIN 512U #define VMW_BALLOON_RATE_FREE_MAX 16384U #define VMW_BALLOON_RATE_FREE_INC 16U @@ -85,6 +101,10 @@ MODULE_LICENSE("GPL"); /* Maximum number of page allocations without yielding processor */ #define VMW_BALLOON_YIELD_THRESHOLD 1024 + +/* + * Hypervisor communication port definitions. + */ #define VMW_BALLOON_HV_PORT 0x5670 #define VMW_BALLOON_HV_MAGIC 0x456c6d6f #define VMW_BALLOON_PROTOCOL_VERSION 2 @@ -125,8 +145,7 @@ MODULE_LICENSE("GPL"); __stat & -1UL; \ }) -#define STATS_INC(stat) (stat)++ - +#ifdef CONFIG_DEBUG_FS struct vmballoon_stats { unsigned int timer; @@ -152,6 +171,11 @@ struct vmballoon_stats { unsigned int guest_type_fail; }; +#define STATS_INC(stat) (stat)++ +#else +#define STATS_INC(stat) +#endif + struct vmballoon { /* list of reserved physical pages */ @@ -174,11 +198,13 @@ struct vmballoon { /* slowdown page allocations for next few cycles */ unsigned int slow_allocation_cycles; +#ifdef CONFIG_DEBUG_FS /* statistics */ struct vmballoon_stats stats; /* debugfs file exporting statistics */ struct dentry *dbg_entry; +#endif struct sysinfo sysinfo; @@ -637,7 +663,7 @@ static void vmballoon_work(struct work_struct *work) } /* - * PROCFS Interface + * DEBUGFS Interface */ #ifdef CONFIG_DEBUG_FS @@ -727,11 +753,11 @@ static inline int vmballoon_debugfs_init(struct vmballoon *b) return 0; } -static inline void vmballoon_debugfs_exit(void) +static inline void vmballoon_debugfs_exit(struct vmballoon *b) { } -#endif /* CONFIG_PROC_FS */ +#endif /* CONFIG_DEBUG_FS */ static int __init vmballoon_init(void) { @@ -750,8 +776,6 @@ static int __init vmballoon_init(void) return -ENOMEM; } - /* initialize global state */ - memset(&balloon, 0, sizeof(balloon)); INIT_LIST_HEAD(&balloon.pages); INIT_LIST_HEAD(&balloon.refused_pages);
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