|
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v5 1/2] x86/mem-sharing: Bulk mem-sharing entire domains
On Sat, Jun 11, 2016 at 5:24 PM, Tamas K Lengyel <tamas@xxxxxxxxxxxxx> wrote:
> Currently mem-sharing can be performed on a page-by-page base from the control
> domain. However, when completely deduplicating (cloning) a VM, this requires
> at least 3 hypercalls per page. As the user has to loop through all pages up
> to max_gpfn, this process is very slow and wasteful.
>
> This patch introduces a new mem_sharing memop for bulk deduplication where
> the user doesn't have to separately nominate each page in both the source and
> destination domain, and the looping over all pages happen in the hypervisor.
> This significantly reduces the overhead of completely deduplicating entire
> domains.
>
> Signed-off-by: Tamas K Lengyel <tamas@xxxxxxxxxxxxx>
> Acked-by: Wei Liu <wei.liu2@xxxxxxxxxx>
> ---
> Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> George Dunlap <george.dunlap@xxxxxxxxxxxxx>
> Jan Beulich <jbeulich@xxxxxxxx>
> Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Missed Cc: here.
>
> v4: Add padding to bulk op and enforce it being 0
> Use correct XSM permission check
> ---
> tools/libxc/include/xenctrl.h | 15 ++++++
> tools/libxc/xc_memshr.c | 19 +++++++
> xen/arch/x86/mm/mem_sharing.c | 121
> ++++++++++++++++++++++++++++++++++++++++++
> xen/include/public/memory.h | 15 +++++-
> 4 files changed, 169 insertions(+), 1 deletion(-)
>
> diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
> index 6ae1a2b..34dcc72 100644
> --- a/tools/libxc/include/xenctrl.h
> +++ b/tools/libxc/include/xenctrl.h
> @@ -2327,6 +2327,21 @@ int xc_memshr_add_to_physmap(xc_interface *xch,
> domid_t client_domain,
> unsigned long client_gfn);
>
> +/* Allows to deduplicate the entire memory of a client domain in bulk. Using
> + * this function is equivalent of calling xc_memshr_nominate_gfn for each gfn
> + * in the two domains followed by xc_memshr_share_gfns. If successfull,
> + * returns the number of shared pages in 'shared'. Both domains must be
> paused.
> + *
> + * May fail with -EINVAL if the source and client domain have different
> + * memory size or if memory sharing is not enabled on either of the domains.
> + * May also fail with -ENOMEM if there isn't enough memory available to store
> + * the sharing metadata before deduplication can happen.
> + */
> +int xc_memshr_bulk_share(xc_interface *xch,
> + domid_t source_domain,
> + domid_t client_domain,
> + uint64_t *shared);
> +
> /* Debug calls: return the number of pages referencing the shared frame
> backing
> * the input argument. Should be one or greater.
> *
> diff --git a/tools/libxc/xc_memshr.c b/tools/libxc/xc_memshr.c
> index deb0aa4..71350d2 100644
> --- a/tools/libxc/xc_memshr.c
> +++ b/tools/libxc/xc_memshr.c
> @@ -181,6 +181,25 @@ int xc_memshr_add_to_physmap(xc_interface *xch,
> return xc_memshr_memop(xch, source_domain, &mso);
> }
>
> +int xc_memshr_bulk_share(xc_interface *xch,
> + domid_t source_domain,
> + domid_t client_domain,
> + uint64_t *shared)
> +{
> + int rc;
> + xen_mem_sharing_op_t mso;
> +
> + memset(&mso, 0, sizeof(mso));
> +
> + mso.op = XENMEM_sharing_op_bulk_share;
> + mso.u.bulk.client_domain = client_domain;
> +
> + rc = xc_memshr_memop(xch, source_domain, &mso);
> + if ( !rc && shared ) *shared = mso.u.bulk.shared;
> +
> + return rc;
> +}
> +
> int xc_memshr_domain_resume(xc_interface *xch,
> domid_t domid)
> {
> diff --git a/xen/arch/x86/mm/mem_sharing.c b/xen/arch/x86/mm/mem_sharing.c
> index a522423..ba06fb0 100644
> --- a/xen/arch/x86/mm/mem_sharing.c
> +++ b/xen/arch/x86/mm/mem_sharing.c
> @@ -1294,6 +1294,54 @@ int relinquish_shared_pages(struct domain *d)
> return rc;
> }
>
> +static int bulk_share(struct domain *d, struct domain *cd, unsigned long
> limit,
> + struct mem_sharing_op_bulk *bulk)
> +{
> + int rc = 0;
> + shr_handle_t sh, ch;
> +
> + while( limit > bulk->start )
> + {
> + /*
> + * We only break out if we run out of memory as individual pages may
> + * legitimately be unsharable and we just want to skip over those.
> + */
> + rc = mem_sharing_nominate_page(d, bulk->start, 0, &sh);
> + if ( rc == -ENOMEM )
> + break;
> + if ( !rc )
> + {
> + rc = mem_sharing_nominate_page(cd, bulk->start, 0, &ch);
> + if ( rc == -ENOMEM )
> + break;
> + if ( !rc )
> + {
> + /* If we get here this should be guaranteed to succeed. */
> + rc = mem_sharing_share_pages(d, bulk->start, sh,
> + cd, bulk->start, ch);
> + ASSERT(!rc);
> + }
> + }
> +
> + /* Check for continuation if it's not the last iteration. */
> + if ( limit > ++bulk->start && hypercall_preempt_check() )
> + {
> + rc = 1;
> + break;
> + }
> + }
> +
> + /*
> + * We only propagate -ENOMEM as individual pages may fail with -EINVAL,
> + * and for bulk sharing we only care if -ENOMEM was encountered so we
> reset
> + * rc here.
> + */
> + if ( rc < 0 && rc != -ENOMEM )
> + rc = 0;
> +
> + return rc;
> +}
> +
> int mem_sharing_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_sharing_op_t) arg)
> {
> int rc;
> @@ -1468,6 +1516,79 @@ int
> mem_sharing_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_sharing_op_t) arg)
> }
> break;
>
> + case XENMEM_sharing_op_bulk_share:
> + {
> + unsigned long max_sgfn, max_cgfn;
> + struct domain *cd;
> +
> + rc = -EINVAL;
> + if( mso.u.bulk._pad[0] || mso.u.bulk._pad[1] ||
> mso.u.bulk._pad[2] )
> + goto out;
> +
> + if ( !mem_sharing_enabled(d) )
> + goto out;
> +
> + rc = rcu_lock_live_remote_domain_by_id(mso.u.bulk.client_domain,
> + &cd);
> + if ( rc )
> + goto out;
> +
> + /*
> + * We reuse XENMEM_sharing_op_share XSM check here as this is
> essentially
> + * the same concept repeated over multiple pages.
> + */
> + rc = xsm_mem_sharing_op(XSM_DM_PRIV, d, cd,
> XENMEM_sharing_op_share);
> + if ( rc )
> + {
> + rcu_unlock_domain(cd);
> + goto out;
> + }
> +
> + if ( !mem_sharing_enabled(cd) )
> + {
> + rcu_unlock_domain(cd);
> + rc = -EINVAL;
> + goto out;
> + }
> +
> + if ( !atomic_read(&d->pause_count) ||
> + !atomic_read(&cd->pause_count) )
> + {
> + rcu_unlock_domain(cd);
> + rc = -EINVAL;
> + goto out;
> + }
> +
> + max_sgfn = domain_get_maximum_gpfn(d);
> + max_cgfn = domain_get_maximum_gpfn(cd);
> +
> + if ( max_sgfn != max_cgfn || max_sgfn < mso.u.bulk.start )
> + {
> + rcu_unlock_domain(cd);
> + rc = -EINVAL;
> + goto out;
> + }
> +
> + rc = bulk_share(d, cd, max_sgfn + 1, &mso.u.bulk);
> + if ( rc > 0 )
> + {
> + if ( __copy_to_guest(arg, &mso, 1) )
> + rc = -EFAULT;
> + else
> + rc =
> hypercall_create_continuation(__HYPERVISOR_memory_op,
> + "lh",
> XENMEM_sharing_op,
> + arg);
> + }
> + else
> + {
> + mso.u.bulk.start = 0;
> + mso.u.bulk.shared = atomic_read(&cd->shr_pages);
> + }
> +
> + rcu_unlock_domain(cd);
> + }
> + break;
> +
> case XENMEM_sharing_op_debug_gfn:
> {
> unsigned long gfn = mso.u.debug.u.gfn;
> diff --git a/xen/include/public/memory.h b/xen/include/public/memory.h
> index 29ec571..084f06e 100644
> --- a/xen/include/public/memory.h
> +++ b/xen/include/public/memory.h
> @@ -465,6 +465,7 @@ DEFINE_XEN_GUEST_HANDLE(xen_mem_access_op_t);
> #define XENMEM_sharing_op_debug_gref 5
> #define XENMEM_sharing_op_add_physmap 6
> #define XENMEM_sharing_op_audit 7
> +#define XENMEM_sharing_op_bulk_share 8
>
> #define XENMEM_SHARING_OP_S_HANDLE_INVALID (-10)
> #define XENMEM_SHARING_OP_C_HANDLE_INVALID (-9)
> @@ -500,7 +501,19 @@ struct xen_mem_sharing_op {
> uint64_aligned_t client_gfn; /* IN: the client gfn */
> uint64_aligned_t client_handle; /* IN: handle to the client page
> */
> domid_t client_domain; /* IN: the client domain id */
> - } share;
> + } share;
> + struct mem_sharing_op_bulk { /* OP_BULK_SHARE */
> + uint64_aligned_t start; /* IN: start gfn. Set to 0 for
> + full deduplication. Field is
> + reset to 0 when hypercall
> + completes */
> + uint64_aligned_t shared; /* OUT: the number of gfns
> + that are shared after this
> + operation, including pages
> + that were already shared */
> + domid_t client_domain; /* IN: the client domain id */
> + uint16_t _pad[3];
> + } bulk;
> struct mem_sharing_op_debug { /* OP_DEBUG_xxx */
> union {
> uint64_aligned_t gfn; /* IN: gfn to debug */
> --
> 2.8.1
>
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel
|
 |
Lists.xenproject.org is hosted with RackSpace, monitoring our |