From: Stefano Stabellini <sstabellini@kernel.org>
To: Julien Grall <julien.grall@arm.com>
Cc: proskurin@sec.in.tum.de, sstabellini@kernel.org,
steve.capper@arm.com, wei.chen@linaro.org,
xen-devel@lists.xen.org
Subject: Re: [PATCH 14/22] xen/arm: p2m: Switch the p2m lock from spinlock to rwlock
Date: Tue, 26 Jul 2016 17:51:32 -0700 (PDT) [thread overview]
Message-ID: <alpine.DEB.2.10.1607261751220.12319@sstabellini-ThinkPad-X260> (raw)
In-Reply-To: <1469031064-23344-15-git-send-email-julien.grall@arm.com>
On Wed, 20 Jul 2016, Julien Grall wrote:
> P2M reads do not require to be serialized. This will add contention
> when PV drivers are using multi-queue because parallel grant
> map/unmaps/copies will happen on DomU's p2m.
>
> Signed-off-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
> I have not done benchark to verify the performance, however a rwlock
> is always an improvement compare to a spinlock when most of the
> access only read data.
>
> It might be possible to convert the rwlock to a per-cpu rwlock which
> show some improvement on x86.
> ---
> xen/arch/arm/p2m.c | 12 ++++++------
> xen/include/asm-arm/p2m.h | 3 ++-
> 2 files changed, 8 insertions(+), 7 deletions(-)
>
> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index d74c249..6136767 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c
> @@ -49,27 +49,27 @@ static bool_t p2m_mapping(lpae_t pte)
>
> static inline void p2m_write_lock(struct p2m_domain *p2m)
> {
> - spin_lock(&p2m->lock);
> + write_lock(&p2m->lock);
> }
>
> static inline void p2m_write_unlock(struct p2m_domain *p2m)
> {
> - spin_unlock(&p2m->lock);
> + write_unlock(&p2m->lock);
> }
>
> static inline void p2m_read_lock(struct p2m_domain *p2m)
> {
> - spin_lock(&p2m->lock);
> + read_lock(&p2m->lock);
> }
>
> static inline void p2m_read_unlock(struct p2m_domain *p2m)
> {
> - spin_unlock(&p2m->lock);
> + read_unlock(&p2m->lock);
> }
>
> static inline int p2m_is_locked(struct p2m_domain *p2m)
> {
> - return spin_is_locked(&p2m->lock);
> + return rw_is_locked(&p2m->lock);
> }
>
> void p2m_dump_info(struct domain *d)
> @@ -1389,7 +1389,7 @@ int p2m_init(struct domain *d)
> struct p2m_domain *p2m = &d->arch.p2m;
> int rc = 0;
>
> - spin_lock_init(&p2m->lock);
> + rwlock_init(&p2m->lock);
> INIT_PAGE_LIST_HEAD(&p2m->pages);
>
> p2m->vmid = INVALID_VMID;
> diff --git a/xen/include/asm-arm/p2m.h b/xen/include/asm-arm/p2m.h
> index 20a220ea..abda70c 100644
> --- a/xen/include/asm-arm/p2m.h
> +++ b/xen/include/asm-arm/p2m.h
> @@ -3,6 +3,7 @@
>
> #include <xen/mm.h>
> #include <xen/radix-tree.h>
> +#include <xen/rwlock.h>
> #include <public/vm_event.h> /* for vm_event_response_t */
> #include <public/memory.h>
> #include <xen/p2m-common.h>
> @@ -20,7 +21,7 @@ extern void memory_type_changed(struct domain *);
> /* Per-p2m-table state */
> struct p2m_domain {
> /* Lock that protects updates to the p2m */
> - spinlock_t lock;
> + rwlock_t lock;
>
> /* Pages used to construct the p2m */
> struct page_list_head pages;
> --
> 1.9.1
>
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next prev parent reply other threads:[~2016-07-27 0:51 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-20 16:10 [PATCH 00/22] xen/arm: P2M clean-up and fixes Julien Grall
2016-07-20 16:10 ` [PATCH 01/22] xen/arm: system: Use the correct parameter name in local_irq_restore Julien Grall
2016-07-22 1:19 ` Stefano Stabellini
2016-07-20 16:10 ` [PATCH 02/22] xen/arm: p2m: Pass the vCPU in parameter to get_page_from_gva Julien Grall
2016-07-22 1:22 ` Stefano Stabellini
2016-07-20 16:10 ` [PATCH 03/22] xen/arm: p2m: Restrict usage of get_page_from_gva to the current vCPU Julien Grall
2016-07-22 1:25 ` Stefano Stabellini
2016-07-20 16:10 ` [PATCH 04/22] xen/arm: p2m: Fix multi-lines coding style comments Julien Grall
2016-07-22 1:26 ` Stefano Stabellini
2016-07-20 16:10 ` [PATCH 05/22] xen/arm: p2m: Clean-up mfn_to_p2m_entry Julien Grall
2016-07-26 22:24 ` Stefano Stabellini
2016-07-20 16:10 ` [PATCH 06/22] xen/arm: p2m: Use the typesafe MFN in mfn_to_p2m_entry Julien Grall
2016-07-26 22:28 ` Stefano Stabellini
2016-07-27 9:54 ` Julien Grall
2016-07-27 18:25 ` Stefano Stabellini
2016-07-27 20:14 ` Julien Grall
2016-07-20 16:10 ` [PATCH 07/22] xen/arm: p2m: Use p2m_is_foreign in get_page_from_gfn to avoid open coding Julien Grall
2016-07-26 22:33 ` Stefano Stabellini
2016-07-20 16:10 ` [PATCH 08/22] xen/arm: p2m: Simplify p2m type check by using bitmask Julien Grall
2016-07-26 22:36 ` Stefano Stabellini
2016-07-20 16:10 ` [PATCH 09/22] xen/arm: p2m: Use a whitelist rather than blacklist in get_page_from_gfn Julien Grall
2016-07-26 22:44 ` Stefano Stabellini
2016-07-27 9:59 ` Julien Grall
2016-07-27 17:56 ` Stefano Stabellini
2016-07-27 17:57 ` Julien Grall
2016-07-20 16:10 ` [PATCH 10/22] xen/arm: p2m: Differentiate cacheable vs non-cacheable MMIO Julien Grall
2016-07-26 22:47 ` Stefano Stabellini
2016-07-20 16:10 ` [PATCH 11/22] xen/arm: p2m: Find the memory attributes based on the p2m type Julien Grall
2016-07-27 0:41 ` Stefano Stabellini
2016-07-27 17:15 ` Julien Grall
2016-07-27 17:55 ` Stefano Stabellini
2016-07-27 20:15 ` Julien Grall
2016-07-20 16:10 ` [PATCH 12/22] xen/arm: p2m: Remove unnecessary locking Julien Grall
2016-07-27 0:47 ` Stefano Stabellini
2016-07-20 16:10 ` [PATCH 13/22] xen/arm: p2m: Introduce p2m_{read, write}_{, un}lock helpers Julien Grall
2016-07-27 0:50 ` Stefano Stabellini
2016-07-20 16:10 ` [PATCH 14/22] xen/arm: p2m: Switch the p2m lock from spinlock to rwlock Julien Grall
2016-07-27 0:51 ` Stefano Stabellini [this message]
2016-07-20 16:10 ` [PATCH 15/22] xen/arm: Don't call p2m_alloc_table from arch_domain_create Julien Grall
2016-07-22 8:32 ` Sergej Proskurin
2016-07-22 9:18 ` Julien Grall
2016-07-22 10:16 ` Sergej Proskurin
2016-07-22 10:26 ` Julien Grall
2016-07-22 10:39 ` Sergej Proskurin
2016-07-22 10:38 ` Julien Grall
2016-07-22 11:05 ` Sergej Proskurin
2016-07-22 13:00 ` Julien Grall
2016-07-23 17:59 ` Sergej Proskurin
2016-07-27 0:54 ` Stefano Stabellini
2016-07-20 16:10 ` [PATCH 16/22] xen/arm: p2m: Move the vttbr field from arch_domain to p2m_domain Julien Grall
2016-07-22 7:46 ` Sergej Proskurin
2016-07-22 9:23 ` Julien Grall
2016-07-27 0:57 ` Stefano Stabellini
2016-07-27 10:00 ` Julien Grall
2016-07-27 17:19 ` Julien Grall
2016-07-20 16:10 ` [PATCH 17/22] xen/arm: p2m: Don't need to restore the state for an idle vCPU Julien Grall
2016-07-22 7:37 ` Sergej Proskurin
2016-07-27 1:05 ` Stefano Stabellini
2016-07-20 16:11 ` [PATCH 18/22] xen/arm: p2m: Rework the context switch to another VTTBR in flush_tlb_domain Julien Grall
2016-07-22 7:51 ` Sergej Proskurin
2016-07-27 1:12 ` Stefano Stabellini
2016-07-27 10:22 ` Julien Grall
2016-07-20 16:11 ` [PATCH 19/22] xen/arm: p2m: Inline p2m_load_VTTBR into p2m_restore_state Julien Grall
2016-07-22 8:07 ` Sergej Proskurin
2016-07-22 9:29 ` Julien Grall
2016-07-27 1:13 ` Stefano Stabellini
2016-07-20 16:11 ` [PATCH 20/22] xen/arm: Don't export flush_tlb_domain Julien Grall
2016-07-22 8:54 ` Sergej Proskurin
2016-07-22 9:30 ` Julien Grall
2016-07-22 10:25 ` Sergej Proskurin
2016-07-22 10:34 ` Julien Grall
2016-07-22 10:46 ` Sergej Proskurin
2016-07-22 10:57 ` Julien Grall
2016-07-22 11:22 ` Sergej Proskurin
2016-07-27 1:14 ` Stefano Stabellini
2016-07-20 16:11 ` [PATCH 21/22] xen/arm: p2m: Replace flush_tlb_domain by p2m_flush_tlb Julien Grall
2016-07-27 1:15 ` Stefano Stabellini
2016-07-20 16:11 ` [PATCH 22/22] xen/arm: p2m: Pass the p2m in parameter rather the domain when it is possible Julien Grall
2016-07-27 1:15 ` Stefano Stabellini
2016-07-22 1:31 ` [PATCH 00/22] xen/arm: P2M clean-up and fixes Stefano Stabellini
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