search for: xb_preload_and_set_bit

...ions(+), 1 deletion(-) diff --git a/include/linux/xbitmap.h b/include/linux/xbitmap.h index b4d8375..eddf0d5e 100644 --- a/include/linux/xbitmap.h +++ b/include/linux/xbitmap.h @@ -33,8 +33,14 @@ static inline void xb_init(struct xb *xb) } int xb_set_bit(struct xb *xb, unsigned long bit); +int xb_preload_and_set_bit(struct xb *xb, unsigned long bit, gfp_t gfp); bool xb_test_bit(const struct xb *xb, unsigned long bit); -int xb_clear_bit(struct xb *xb, unsigned long bit); +void xb_clear_bit(struct xb *xb, unsigned long bit); +unsigned long xb_find_next_set_bit(struct xb *xb, unsigned long start, + unsigne...

...<mst at redhat.com> Cc: Tetsuo Handa <penguin-kernel at I-love.SAKURA.ne.jp> v16->v17 ChangeLog: 1) xb_preload: allocate ida bitmap before __radix_tree_preload() to avoid kmalloc with preemption disabled. Also change this function to return with preemption not disabled on error. 2) xb_preload_and_set_bit: a wrapper of xb_preload and xb_set_bit, for the convenience of usage. v15->v16 ChangeLog: 1) coding style - separate small functions for bit set/clear/test; 2) Clear a range of bits in a more efficient way: A) clear a range of bits from the same ida bitmap directly rather than search...

On Tue, Dec 12, 2017 at 07:55:55PM +0800, Wei Wang wrote: > +int xb_preload_and_set_bit(struct xb *xb, unsigned long bit, gfp_t gfp); I'm struggling to understand when one would use this. The xb_ API requires you to handle your own locking. But specifying GFP flags here implies you can sleep. So ... um ... there's no locking? > +void xb_clear_bit_range(struct xb *xb, u...

On Tue, Dec 12, 2017 at 07:55:55PM +0800, Wei Wang wrote: > +int xb_preload_and_set_bit(struct xb *xb, unsigned long bit, gfp_t gfp); I'm struggling to understand when one would use this. The xb_ API requires you to handle your own locking. But specifying GFP flags here implies you can sleep. So ... um ... there's no locking? > +void xb_clear_bit_range(struct xb *xb, u...

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

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

...gt; + struct page *page, > + unsigned long *pfn_min, > + unsigned long *pfn_max) > +{ > + unsigned long pfn = page_to_pfn(page); > + int ret; > + > + *pfn_min = min(pfn, *pfn_min); > + *pfn_max = max(pfn, *pfn_max); > + > + do { > + ret = xb_preload_and_set_bit(&vb->page_xb, pfn, > + GFP_NOWAIT | __GFP_NOWARN); > + } while (unlikely(ret == -EAGAIN)); what exactly does this loop do? Does this wait forever until there is some free memory? why GFP_NOWAIT? > + > + return ret; > +} > + > static unsigned fill_balloon(stru...

...gt; + struct page *page, > + unsigned long *pfn_min, > + unsigned long *pfn_max) > +{ > + unsigned long pfn = page_to_pfn(page); > + int ret; > + > + *pfn_min = min(pfn, *pfn_min); > + *pfn_max = max(pfn, *pfn_max); > + > + do { > + ret = xb_preload_and_set_bit(&vb->page_xb, pfn, > + GFP_NOWAIT | __GFP_NOWARN); > + } while (unlikely(ret == -EAGAIN)); what exactly does this loop do? Does this wait forever until there is some free memory? why GFP_NOWAIT? > + > + return ret; > +} > + > static unsigned fill_balloon(stru...

...lot, bitmap, NULL, + NULL); + return 0; + } + bitmap = this_cpu_xchg(ida_bitmap, NULL); + if (!bitmap) + return -EAGAIN; + memset(bitmap, 0, sizeof(*bitmap)); + __radix_tree_replace(root, node, slot, bitmap, NULL, NULL); + } + + __set_bit(bit, bitmap->bitmap); + return 0; +} + +int xb_preload_and_set_bit(struct xb *xb, unsigned long bit, gfp_t gfp) +{ + int ret = 0; + + if (!xb_preload(gfp)) + return -ENOMEM; + + ret = xb_set_bit(xb, bit); + xb_preload_end(); + + return ret; +} + +bool xb_test_bit(struct xb *xb, unsigned long bit) +{ + unsigned long index = bit / IDA_BITMAP_BITS; + const struct ra...

On 12/16/2017 07:28 PM, Tetsuo Handa wrote: > Wei Wang wrote: >> On 12/16/2017 02:42 AM, Matthew Wilcox wrote: >>> On Tue, Dec 12, 2017 at 07:55:55PM +0800, Wei Wang wrote: >>>> +int xb_preload_and_set_bit(struct xb *xb, unsigned long bit, gfp_t gfp); >>> I'm struggling to understand when one would use this. The xb_ API >>> requires you to handle your own locking. But specifying GFP flags >>> here implies you can sleep. So ... um ... there's no locking? >>...

...unsigned long *pfn_min, > > + unsigned long *pfn_max) > > +{ > > + unsigned long pfn = page_to_pfn(page); > > + int ret; > > + > > + *pfn_min = min(pfn, *pfn_min); > > + *pfn_max = max(pfn, *pfn_max); > > + > > + do { > > + ret = xb_preload_and_set_bit(&vb->page_xb, pfn, > > + GFP_NOWAIT | __GFP_NOWARN); > > It is a bit of pity that __GFP_NOWARN here is applied to only xb_preload(). > Memory allocation by xb_set_bit() will after all emit warnings. Maybe > > xb_init(&vb->page_xb); > vb->page_...

I'm commenting without understanding the logic. Wei Wang wrote: > + > +bool xb_preload(gfp_t gfp); > + Want __must_check annotation, for __radix_tree_preload() is marked with __must_check annotation. By error failing to check result of xb_preload() will lead to preemption kept disabled unexpectedly. > +int xb_set_bit(struct xb *xb, unsigned long bit) > +{ > + int err;

I'm commenting without understanding the logic. Wei Wang wrote: > + > +bool xb_preload(gfp_t gfp); > + Want __must_check annotation, for __radix_tree_preload() is marked with __must_check annotation. By error failing to check result of xb_preload() will lead to preemption kept disabled unexpectedly. > +int xb_set_bit(struct xb *xb, unsigned long bit) > +{ > + int err;

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

...+static inline int 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); + int ret; + + *pfn_min = min(pfn, *pfn_min); + *pfn_max = max(pfn, *pfn_max); + + do { + ret = xb_preload_and_set_bit(&vb->page_xb, pfn, + GFP_NOWAIT | __GFP_NOWARN); + } while (unlikely(ret == -EAGAIN)); + + return ret; +} + static unsigned fill_balloon(struct virtio_balloon *vb, size_t num) { unsigned num_allocated_pages; unsigned num_pfns; struct page *page; LIST_HEAD(pages); + bool us...

...+static inline int 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); + int ret; + + *pfn_min = min(pfn, *pfn_min); + *pfn_max = max(pfn, *pfn_max); + + do { + ret = xb_preload_and_set_bit(&vb->page_xb, pfn, GFP_KERNEL); + } while (unlikely(ret == -EAGAIN)); + + return ret; +} + static unsigned fill_balloon(struct virtio_balloon *vb, size_t num) { unsigned num_allocated_pages; unsigned int num_pfns; struct page *page; LIST_HEAD(pages); + bool use_sg = virtio_has_feat...