From mboxrd@z Thu Jan 1 00:00:00 1970 From: Huang Ying Subject: Re: [PATCH 6/7] ACPI: Page based coalescing of I/O remappings optimization Date: Fri, 22 Oct 2010 09:03:54 +0800 Message-ID: <1287709434.2862.25.camel@yhuang-dev> References: <20101021201916.9220.5711.stgit@bob.kio> <20101021202414.9220.71053.stgit@bob.kio> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: Received: from mga11.intel.com ([192.55.52.93]:4350 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750968Ab0JVBD4 (ORCPT ); Thu, 21 Oct 2010 21:03:56 -0400 In-Reply-To: <20101021202414.9220.71053.stgit@bob.kio> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Myron Stowe Cc: "lenb@kernel.org" , "linux-acpi@vger.kernel.org" , "ak@linux.intel.com" Hi, Myron, On Fri, 2010-10-22 at 04:24 +0800, Myron Stowe wrote: > This patch optimizes ACPI MMIO remappings by keeping track of the > remappings on a PAGE_SIZE granularity. > > When an ioremap() occurs, the underlying infrastructure works on a 'page' > based granularity. As such, an ioremap() request for 1 byte for example, > will end up mapping in an entire (PAGE_SIZE) page. Huang Ying took > advantage of this in commit 15651291a2f8c11e7e6a42d8bfde7a213ff13262 by > checking if subsequent ioremap() requests reside within any of the list's > existing remappings still in place, and if so, incrementing a reference > count on the existing mapping as opposed to performing another ioremap(). > > > Signed-off-by: Myron Stowe > --- > > drivers/acpi/osl.c | 62 +++++++++++++++++++++++++++++++++++++++++++--------- > 1 files changed, 51 insertions(+), 11 deletions(-) > > diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c > index 3282689..885e222 100644 > --- a/drivers/acpi/osl.c > +++ b/drivers/acpi/osl.c > @@ -104,6 +104,7 @@ struct acpi_ioremap { > void __iomem *virt; > acpi_physical_address phys; > acpi_size size; > + struct kref ref; > }; > > static LIST_HEAD(acpi_ioremaps); > @@ -245,15 +246,28 @@ acpi_physical_address __init acpi_os_get_root_pointer(void) > } > > /* Must be called with 'acpi_ioremap_lock' or RCU read lock held. */ > -static void __iomem * > -acpi_map_vaddr_lookup(acpi_physical_address phys, acpi_size size) > +static struct acpi_ioremap * > +acpi_map_lookup(acpi_physical_address phys, acpi_size size) > { > struct acpi_ioremap *map; > > list_for_each_entry_rcu(map, &acpi_ioremaps, list) > if (map->phys <= phys && > phys + size <= map->phys + map->size) > - return map->virt + (phys - map->phys); > + return map; > + > + return NULL; > +} > + > +/* Must be called with 'acpi_ioremap_lock' or RCU read lock held. */ > +static void __iomem * > +acpi_map_vaddr_lookup(acpi_physical_address phys, unsigned int size) > +{ > + struct acpi_ioremap *map; > + > + map = acpi_map_lookup(phys, size); > + if (map) > + return map->virt + (phys - map->phys); > > return NULL; > } > @@ -265,7 +279,8 @@ acpi_map_lookup_virt(void __iomem *virt, acpi_size size) > struct acpi_ioremap *map; > > list_for_each_entry_rcu(map, &acpi_ioremaps, list) > - if (map->virt == virt && map->size == size) > + if (map->virt <= virt && > + virt + size <= map->virt + map->size) > return map; > > return NULL; > @@ -274,9 +289,10 @@ acpi_map_lookup_virt(void __iomem *virt, acpi_size size) > void __iomem *__init_refok > acpi_os_map_memory(acpi_physical_address phys, acpi_size size) > { > - struct acpi_ioremap *map; > - unsigned long flags; > + struct acpi_ioremap *map, *tmp_map; > + unsigned long flags, pg_sz; > void __iomem *virt; > + phys_addr_t pg_off; > > if (phys > ULONG_MAX) { > printk(KERN_ERR PREFIX "Cannot map memory that high\n"); > @@ -290,7 +306,9 @@ acpi_os_map_memory(acpi_physical_address phys, acpi_size size) > if (!map) > return NULL; > > - virt = ioremap(phys, size); > + pg_off = round_down(phys, PAGE_SIZE); > + pg_sz = round_up(phys + size, PAGE_SIZE) - pg_off; > + virt = ioremap(pg_off, pg_sz); > if (!virt) { > kfree(map); > return NULL; Why not check the existing map (that is, acpi_map_lookup()) before the ioremap()? In APEI tables, several GAS may be in same page, so we need ioremap() for the first page only. Best Regards, Huang Ying > @@ -298,21 +316,40 @@ acpi_os_map_memory(acpi_physical_address phys, acpi_size size) > > INIT_LIST_HEAD(&map->list); > map->virt = virt; > - map->phys = phys; > - map->size = size; > + map->phys = pg_off; > + map->size = pg_sz; > + kref_init(&map->ref); > > spin_lock_irqsave(&acpi_ioremap_lock, flags); > + /* Check if page has already been mapped. */ > + tmp_map = acpi_map_lookup(phys, size); > + if (tmp_map) { > + kref_get(&tmp_map->ref); > + spin_unlock_irqrestore(&acpi_ioremap_lock, flags); > + iounmap(map->virt); > + kfree(map); > + return tmp_map->virt + (phys - tmp_map->phys); > + } > list_add_tail_rcu(&map->list, &acpi_ioremaps); > spin_unlock_irqrestore(&acpi_ioremap_lock, flags); > > - return virt; > + return map->virt + (phys - map->phys); > } > EXPORT_SYMBOL_GPL(acpi_os_map_memory); > > +static void acpi_kref_del_iomap(struct kref *ref) > +{ > + struct acpi_ioremap *map; > + > + map = container_of(ref, struct acpi_ioremap, ref); > + list_del_rcu(&map->list); > +} > + > void __ref acpi_os_unmap_memory(void __iomem *virt, acpi_size size) > { > struct acpi_ioremap *map; > unsigned long flags; > + int del; > > if (!acpi_gbl_permanent_mmap) { > __acpi_unmap_table(virt, size); > @@ -328,9 +365,12 @@ void __ref acpi_os_unmap_memory(void __iomem *virt, acpi_size size) > return; > } > > - list_del_rcu(&map->list); > + del = kref_put(&map->ref, acpi_kref_del_iomap); > spin_unlock_irqrestore(&acpi_ioremap_lock, flags); > > + if (!del) > + return; > + > synchronize_rcu(); > iounmap(map->virt); > kfree(map); >