search for: this_cpu_cmpxchg

...* 2 - 1) > + > > ... > > +void xb_preload(gfp_t gfp) > +{ > + __radix_tree_preload(gfp, XB_PRELOAD_SIZE); > + if (!this_cpu_read(ida_bitmap)) { > + struct ida_bitmap *bitmap = kmalloc(sizeof(*bitmap), gfp); > + > + if (!bitmap) > + return; > + bitmap = this_cpu_cmpxchg(ida_bitmap, NULL, bitmap); > + kfree(bitmap); > + } > +} > +EXPORT_SYMBOL(xb_preload); Please document the exported API. It's conventional to do this in kerneldoc but for some reason kerneldoc makes people write uninteresting and unuseful documentation. Be sure to cover the *use...

...* 2 - 1) > + > > ... > > +void xb_preload(gfp_t gfp) > +{ > + __radix_tree_preload(gfp, XB_PRELOAD_SIZE); > + if (!this_cpu_read(ida_bitmap)) { > + struct ida_bitmap *bitmap = kmalloc(sizeof(*bitmap), gfp); > + > + if (!bitmap) > + return; > + bitmap = this_cpu_cmpxchg(ida_bitmap, NULL, bitmap); > + kfree(bitmap); > + } > +} > +EXPORT_SYMBOL(xb_preload); Please document the exported API. It's conventional to do this in kerneldoc but for some reason kerneldoc makes people write uninteresting and unuseful documentation. Be sure to cover the *use...

On Sat, Sep 30, 2017 at 12:05:52PM +0800, Wei Wang wrote: > +static inline void xb_set_page(struct virtio_balloon *vb, > + struct page *page, > + unsigned long *pfn_min, > + unsigned long *pfn_max) > +{ > + unsigned long pfn = page_to_pfn(page); > + > + *pfn_min = min(pfn, *pfn_min); > + *pfn_max = max(pfn, *pfn_max); > +

On Sat, Sep 30, 2017 at 12:05:52PM +0800, Wei Wang wrote: > +static inline void xb_set_page(struct virtio_balloon *vb, > + struct page *page, > + unsigned long *pfn_min, > + unsigned long *pfn_max) > +{ > + unsigned long pfn = page_to_pfn(page); > + > + *pfn_min = min(pfn, *pfn_min); > + *pfn_max = max(pfn, *pfn_max); > +

...t be expected, thanks. I plan to change it like this: bool xb_preload(gfp_t gfp) { if (!this_cpu_read(ida_bitmap)) { struct ida_bitmap *bitmap = kmalloc(sizeof(*bitmap), gfp); if (!bitmap) return false; bitmap = this_cpu_cmpxchg(ida_bitmap, NULL, bitmap); kfree(bitmap); } if (__radix_tree_preload(gfp, XB_PRELOAD_SIZE) < 0) return false; return true; } Best, Wei

...ool xb_preload(gfp_t gfp) >> { >> if (!this_cpu_read(ida_bitmap)) { >> struct ida_bitmap *bitmap = kmalloc(sizeof(*bitmap), gfp); >> >> if (!bitmap) >> return false; >> bitmap = this_cpu_cmpxchg(ida_bitmap, NULL, bitmap); >> kfree(bitmap); >> } > Excuse me, but you are allocating per-CPU memory when running CPU might > change at this line? What happens if running CPU has changed at this line? > Will it work even with new CPU's ida_bitmap ==...

...n path and fold all xbitmap patches into one, and > post only one xbitmap patch without virtio-balloon changes? > > . > > I still think we don't need xb_preload()/xb_preload_end(). Why would you think preload is not needed? The bitmap is allocated via preload "bitmap = this_cpu_cmpxchg(ida_bitmap, NULL, bitmap);", this allocated bitmap would be used in xb_set_bit(). > I think xb_find_set() has a bug in !node path. I think we can probably remove the "!node" path for now. It would be good to get the fundamental part in first, and leave optimization to come a...

...n path and fold all xbitmap patches into one, and > post only one xbitmap patch without virtio-balloon changes? > > . > > I still think we don't need xb_preload()/xb_preload_end(). Why would you think preload is not needed? The bitmap is allocated via preload "bitmap = this_cpu_cmpxchg(ida_bitmap, NULL, bitmap);", this allocated bitmap would be used in xb_set_bit(). > I think xb_find_set() has a bug in !node path. I think we can probably remove the "!node" path for now. It would be good to get the fundamental part in first, and leave optimization to come a...

...ap) - return; + return false; + /* + * The per-CPU variable is updated with preemption enabled. + * If the calling task is unlucky to be scheduled to another + * CPU which has no ida_bitmap allocation, it will be detected + * when setting a bit (i.e. __xb_set_bit()). + */ bitmap = this_cpu_cmpxchg(ida_bitmap, NULL, bitmap); kfree(bitmap); } + + if (__radix_tree_preload(gfp, XB_PRELOAD_SIZE) < 0) + return false; + + return true; } EXPORT_SYMBOL(xb_preload); diff --git a/lib/xbitmap.c b/lib/xbitmap.c index 2b547a73..182aa29 100644 --- a/lib/xbitmap.c +++ b/lib/xbitmap.c @@ -39,8 +...

...0 @@ int ida_pre_get(struct ida *ida, gfp_t gfp) } EXPORT_SYMBOL(ida_pre_get); +void xb_preload(gfp_t gfp) +{ + __radix_tree_preload(gfp, XB_PRELOAD_SIZE); + if (!this_cpu_read(ida_bitmap)) { + struct ida_bitmap *bitmap = kmalloc(sizeof(*bitmap), gfp); + + if (!bitmap) + return; + bitmap = this_cpu_cmpxchg(ida_bitmap, NULL, bitmap); + kfree(bitmap); + } +} +EXPORT_SYMBOL(xb_preload); + +int xb_set_bit(struct xb *xb, unsigned long bit) +{ + int err; + unsigned long index = bit / IDA_BITMAP_BITS; + struct radix_tree_root *root = &xb->xbrt; + struct radix_tree_node *node; + void **slot; + struct...

...0 @@ int ida_pre_get(struct ida *ida, gfp_t gfp) } EXPORT_SYMBOL(ida_pre_get); +void xb_preload(gfp_t gfp) +{ + __radix_tree_preload(gfp, XB_PRELOAD_SIZE); + if (!this_cpu_read(ida_bitmap)) { + struct ida_bitmap *bitmap = kmalloc(sizeof(*bitmap), gfp); + + if (!bitmap) + return; + bitmap = this_cpu_cmpxchg(ida_bitmap, NULL, bitmap); + kfree(bitmap); + } +} +EXPORT_SYMBOL(xb_preload); + void __rcu **idr_get_free_cmn(struct radix_tree_root *root, struct radix_tree_iter *iter, gfp_t gfp, unsigned long max) diff --git a/lib/xbitmap.c b/lib/xbitmap.c new file mode 100644 index 000000...

...0 @@ int ida_pre_get(struct ida *ida, gfp_t gfp) } EXPORT_SYMBOL(ida_pre_get); +void xb_preload(gfp_t gfp) +{ + __radix_tree_preload(gfp, XB_PRELOAD_SIZE); + if (!this_cpu_read(ida_bitmap)) { + struct ida_bitmap *bitmap = kmalloc(sizeof(*bitmap), gfp); + + if (!bitmap) + return; + bitmap = this_cpu_cmpxchg(ida_bitmap, NULL, bitmap); + kfree(bitmap); + } +} +EXPORT_SYMBOL(xb_preload); + void __rcu **idr_get_free_cmn(struct radix_tree_root *root, struct radix_tree_iter *iter, gfp_t gfp, unsigned long max) diff --git a/lib/xbitmap.c b/lib/xbitmap.c new file mode 100644 index 000000...

...+ if (!bitmap) + return false; + /* + * The per-CPU variable is updated with preemption enabled. + * If the calling task is unlucky to be scheduled to another + * CPU which has no ida_bitmap allocation, it will be detected + * when setting a bit (i.e. __xb_set_bit()). + */ + bitmap = this_cpu_cmpxchg(ida_bitmap, NULL, bitmap); + kfree(bitmap); + } + + if (__radix_tree_preload(gfp, XB_PRELOAD_SIZE) < 0) + return false; + + return true; +} +EXPORT_SYMBOL(xb_preload); + +/** * radix_tree_iter_delete - delete the entry at this iterator position * @root: radix tree root * @iter: iterator...

...+ if (!bitmap) + return -ENOMEM; + /* + * The per-CPU variable is updated with preemption enabled. + * If the calling task is unlucky to be scheduled to another + * CPU which has no ida_bitmap allocation, it will be detected + * when setting a bit (i.e. xb_set_bit()). + */ + bitmap = this_cpu_cmpxchg(ida_bitmap, NULL, bitmap); + kfree(bitmap); + } + + return __radix_tree_preload(gfp, XB_PRELOAD_SIZE); +} +EXPORT_SYMBOL(xb_preload); + void __rcu **idr_get_free_cmn(struct radix_tree_root *root, struct radix_tree_iter *iter, gfp_t gfp, unsigned long max) diff --git a/lib/xbit...

...+ if (!bitmap) + return -ENOMEM; + /* + * The per-CPU variable is updated with preemption enabled. + * If the calling task is unlucky to be scheduled to another + * CPU which has no ida_bitmap allocation, it will be detected + * when setting a bit (i.e. xb_set_bit()). + */ + bitmap = this_cpu_cmpxchg(ida_bitmap, NULL, bitmap); + kfree(bitmap); + } + + return __radix_tree_preload(gfp, XB_PRELOAD_SIZE); +} +EXPORT_SYMBOL(xb_preload); + void __rcu **idr_get_free_cmn(struct radix_tree_root *root, struct radix_tree_iter *iter, gfp_t gfp, unsigned long max) diff --git a/lib/xbit...

This patch series enhances the existing virtio-balloon with the following new features: 1) fast ballooning: transfer ballooned pages between the guest and host in chunks using sgs, instead of one by one; and 2) free_page_vq: a new virtqueue to report guest free pages to the host. The second feature can be used to accelerate live migration of VMs. Here are some details: Live migration needs to

This patch series enhances the existing virtio-balloon with the following new features: 1) fast ballooning: transfer ballooned pages between the guest and host in chunks using sgs, instead of one by one; and 2) free_page_vq: a new virtqueue to report guest free pages to the host. The second feature can be used to accelerate live migration of VMs. Here are some details: Live migration needs to

This patch series enhances the existing virtio-balloon with the following new features: 1) fast ballooning: transfer ballooned pages between the guest and host in chunks using sgs, instead of one array each time; and 2) free page block reporting: a new virtqueue to report guest free pages to the host. The second feature can be used to accelerate live migration of VMs. Here are some details: Live

This patch series enhances the existing virtio-balloon with the following new features: 1) fast ballooning: transfer ballooned pages between the guest and host in chunks using sgs, instead of one array each time; and 2) free page block reporting: a new virtqueue to report guest free pages to the host. The second feature can be used to accelerate live migration of VMs. Here are some details: Live

This patch series enhances the existing virtio-balloon with the following new features: 1) fast ballooning: transfer ballooned pages between the guest and host in chunks using sgs, instead of one array each time; and 2) free page block reporting: a new virtqueue to report guest free pages to the host. The second feature can be used to accelerate live migration of VMs. Here are some details: Live