<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-toradex.git/drivers/net/mlx4, branch v2.6.27.31</title>
<subtitle>Linux kernel for Apalis and Colibri modules</subtitle>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/'/>
<entry>
<title>IB/mlx4: Fix up fast register page list format</title>
<updated>2008-09-15T21:25:23+00:00</updated>
<author>
<name>Vladimir Sokolovsky</name>
<email>vlad@mellanox.co.il</email>
</author>
<published>2008-09-15T21:25:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=29bdc88384c2b24e37e5760df0dc898546083d6b'/>
<id>29bdc88384c2b24e37e5760df0dc898546083d6b</id>
<content type='text'>
Byte swap the addresses in the page list for fast register work requests
to big endian to match what the HCA expectx.  Also, the addresses must
have the "present" bit set so that the HCA knows it can access them.
Otherwise the HCA will fault the first time it accesses the memory
region.

Signed-off-by: Vladimir Sokolovsky &lt;vlad@mellanox.co.il&gt;
Signed-off-by: Roland Dreier &lt;rolandd@cisco.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Byte swap the addresses in the page list for fast register work requests
to big endian to match what the HCA expectx.  Also, the addresses must
have the "present" bit set so that the HCA knows it can access them.
Otherwise the HCA will fault the first time it accesses the memory
region.

Signed-off-by: Vladimir Sokolovsky &lt;vlad@mellanox.co.il&gt;
Signed-off-by: Roland Dreier &lt;rolandd@cisco.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mlx4_core: Set RAE and init mtt_sz field in FRMR MPT entries</title>
<updated>2008-09-02T20:38:29+00:00</updated>
<author>
<name>Vladimir Sokolovsky</name>
<email>vlad@mellanox.co.il</email>
</author>
<published>2008-09-02T20:38:29+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=c9257433f2eaf8803a1f3d3be5d984232db41ffe'/>
<id>c9257433f2eaf8803a1f3d3be5d984232db41ffe</id>
<content type='text'>
Set the RAE (remote access enable) bit and correctly initialize the
MTT size in MPT entries being set up for fast register memory
regions.  Otherwise the callers can't enable remote access and in fact
can't fast register at all (since the HCA will think no MTT entries
are allocated).

Signed-off-by: Vladimir Sokolovsky &lt;vlad@mellanox.co.il&gt;
Signed-off-by: Roland Dreier &lt;rolandd@cisco.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Set the RAE (remote access enable) bit and correctly initialize the
MTT size in MPT entries being set up for fast register memory
regions.  Otherwise the callers can't enable remote access and in fact
can't fast register at all (since the HCA will think no MTT entries
are allocated).

Signed-off-by: Vladimir Sokolovsky &lt;vlad@mellanox.co.il&gt;
Signed-off-by: Roland Dreier &lt;rolandd@cisco.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/roland/infiniband</title>
<updated>2008-07-27T03:40:36+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2008-07-27T03:40:36+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=8be1a6d6c77ab4532e4476fdb8177030ef48b52c'/>
<id>8be1a6d6c77ab4532e4476fdb8177030ef48b52c</id>
<content type='text'>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/roland/infiniband:
  mlx4: Update/add Mellanox Technologies copyright lines to mlx4 driver files
  mlx4_core: Add VLAN tag field to WQE control segment struct
  RDMA/nes: CM connection setup/teardown rework
  IPoIB: Correct help text for INFINIBAND_IPOIB_DEBUG
  IPoIB/cm: Connected mode is no longer EXPERIMENTAL
  RDMA/ucm: BKL is not needed for ib_ucm_open()
  RDMA/ucma: BKL is not needed for ucma_open()
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/roland/infiniband:
  mlx4: Update/add Mellanox Technologies copyright lines to mlx4 driver files
  mlx4_core: Add VLAN tag field to WQE control segment struct
  RDMA/nes: CM connection setup/teardown rework
  IPoIB: Correct help text for INFINIBAND_IPOIB_DEBUG
  IPoIB/cm: Connected mode is no longer EXPERIMENTAL
  RDMA/ucm: BKL is not needed for ib_ucm_open()
  RDMA/ucma: BKL is not needed for ucma_open()
</pre>
</div>
</content>
</entry>
<entry>
<title>dma-mapping: add the device argument to dma_mapping_error()</title>
<updated>2008-07-26T19:00:03+00:00</updated>
<author>
<name>FUJITA Tomonori</name>
<email>fujita.tomonori@lab.ntt.co.jp</email>
</author>
<published>2008-07-26T02:44:49+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=8d8bb39b9eba32dd70e87fd5ad5c5dd4ba118e06'/>
<id>8d8bb39b9eba32dd70e87fd5ad5c5dd4ba118e06</id>
<content type='text'>
Add per-device dma_mapping_ops support for CONFIG_X86_64 as POWER
architecture does:

This enables us to cleanly fix the Calgary IOMMU issue that some devices
are not behind the IOMMU (http://lkml.org/lkml/2008/5/8/423).

I think that per-device dma_mapping_ops support would be also helpful for
KVM people to support PCI passthrough but Andi thinks that this makes it
difficult to support the PCI passthrough (see the above thread).  So I
CC'ed this to KVM camp.  Comments are appreciated.

A pointer to dma_mapping_ops to struct dev_archdata is added.  If the
pointer is non NULL, DMA operations in asm/dma-mapping.h use it.  If it's
NULL, the system-wide dma_ops pointer is used as before.

If it's useful for KVM people, I plan to implement a mechanism to register
a hook called when a new pci (or dma capable) device is created (it works
with hot plugging).  It enables IOMMUs to set up an appropriate
dma_mapping_ops per device.

The major obstacle is that dma_mapping_error doesn't take a pointer to the
device unlike other DMA operations.  So x86 can't have dma_mapping_ops per
device.  Note all the POWER IOMMUs use the same dma_mapping_error function
so this is not a problem for POWER but x86 IOMMUs use different
dma_mapping_error functions.

The first patch adds the device argument to dma_mapping_error.  The patch
is trivial but large since it touches lots of drivers and dma-mapping.h in
all the architecture.

This patch:

dma_mapping_error() doesn't take a pointer to the device unlike other DMA
operations.  So we can't have dma_mapping_ops per device.

Note that POWER already has dma_mapping_ops per device but all the POWER
IOMMUs use the same dma_mapping_error function.  x86 IOMMUs use device
argument.

[akpm@linux-foundation.org: fix sge]
[akpm@linux-foundation.org: fix svc_rdma]
[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: fix bnx2x]
[akpm@linux-foundation.org: fix s2io]
[akpm@linux-foundation.org: fix pasemi_mac]
[akpm@linux-foundation.org: fix sdhci]
[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: fix sparc]
[akpm@linux-foundation.org: fix ibmvscsi]
Signed-off-by: FUJITA Tomonori &lt;fujita.tomonori@lab.ntt.co.jp&gt;
Cc: Muli Ben-Yehuda &lt;muli@il.ibm.com&gt;
Cc: Andi Kleen &lt;andi@firstfloor.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Ingo Molnar &lt;mingo@elte.hu&gt;
Cc: Avi Kivity &lt;avi@qumranet.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Add per-device dma_mapping_ops support for CONFIG_X86_64 as POWER
architecture does:

This enables us to cleanly fix the Calgary IOMMU issue that some devices
are not behind the IOMMU (http://lkml.org/lkml/2008/5/8/423).

I think that per-device dma_mapping_ops support would be also helpful for
KVM people to support PCI passthrough but Andi thinks that this makes it
difficult to support the PCI passthrough (see the above thread).  So I
CC'ed this to KVM camp.  Comments are appreciated.

A pointer to dma_mapping_ops to struct dev_archdata is added.  If the
pointer is non NULL, DMA operations in asm/dma-mapping.h use it.  If it's
NULL, the system-wide dma_ops pointer is used as before.

If it's useful for KVM people, I plan to implement a mechanism to register
a hook called when a new pci (or dma capable) device is created (it works
with hot plugging).  It enables IOMMUs to set up an appropriate
dma_mapping_ops per device.

The major obstacle is that dma_mapping_error doesn't take a pointer to the
device unlike other DMA operations.  So x86 can't have dma_mapping_ops per
device.  Note all the POWER IOMMUs use the same dma_mapping_error function
so this is not a problem for POWER but x86 IOMMUs use different
dma_mapping_error functions.

The first patch adds the device argument to dma_mapping_error.  The patch
is trivial but large since it touches lots of drivers and dma-mapping.h in
all the architecture.

This patch:

dma_mapping_error() doesn't take a pointer to the device unlike other DMA
operations.  So we can't have dma_mapping_ops per device.

Note that POWER already has dma_mapping_ops per device but all the POWER
IOMMUs use the same dma_mapping_error function.  x86 IOMMUs use device
argument.

[akpm@linux-foundation.org: fix sge]
[akpm@linux-foundation.org: fix svc_rdma]
[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: fix bnx2x]
[akpm@linux-foundation.org: fix s2io]
[akpm@linux-foundation.org: fix pasemi_mac]
[akpm@linux-foundation.org: fix sdhci]
[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: fix sparc]
[akpm@linux-foundation.org: fix ibmvscsi]
Signed-off-by: FUJITA Tomonori &lt;fujita.tomonori@lab.ntt.co.jp&gt;
Cc: Muli Ben-Yehuda &lt;muli@il.ibm.com&gt;
Cc: Andi Kleen &lt;andi@firstfloor.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Ingo Molnar &lt;mingo@elte.hu&gt;
Cc: Avi Kivity &lt;avi@qumranet.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mlx4: Update/add Mellanox Technologies copyright lines to mlx4 driver files</title>
<updated>2008-07-25T17:32:52+00:00</updated>
<author>
<name>Jack Morgenstein</name>
<email>jackm@dev.mellanox.co.il</email>
</author>
<published>2008-07-25T17:32:52+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=51a379d0c8f7a6db7c9e3c9c770d90a6d2d1ef9b'/>
<id>51a379d0c8f7a6db7c9e3c9c770d90a6d2d1ef9b</id>
<content type='text'>
Update existing Mellanox copyright lines to 2008, and add such lines
to files where they are missing.

Signed-off-by: Jack Morgenstein &lt;jackm@dev.mellanox.co.il&gt;
Signed-off-by: Roland Dreier &lt;rolandd@cisco.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Update existing Mellanox copyright lines to 2008, and add such lines
to files where they are missing.

Signed-off-by: Jack Morgenstein &lt;jackm@dev.mellanox.co.il&gt;
Signed-off-by: Roland Dreier &lt;rolandd@cisco.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/roland/infiniband</title>
<updated>2008-07-24T19:56:07+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2008-07-24T19:56:07+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=5c402355adf8f920531f02099f4ec0d2bccd4c64'/>
<id>5c402355adf8f920531f02099f4ec0d2bccd4c64</id>
<content type='text'>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/roland/infiniband:
  MAINTAINERS: Remove Glenn Streiff from NetEffect entry
  mlx4_core: Improve error message when not enough UAR pages are available
  IB/mlx4: Add support for memory management extensions and local DMA L_Key
  IB/mthca: Keep free count for MTT buddy allocator
  mlx4_core: Keep free count for MTT buddy allocator
  mlx4_code: Add missing FW status return code
  IB/mlx4: Rename struct mlx4_lso_seg to mlx4_wqe_lso_seg
  mlx4_core: Add module parameter to enable QoS support
  RDMA/iwcm: Remove IB_ACCESS_LOCAL_WRITE from remote QP attributes
  IPoIB: Include err code in trace message for ib_sa_path_rec_get() failures
  IB/sa_query: Check if sm_ah is NULL in ib_sa_remove_one()
  IB/ehca: Release mutex in error path of alloc_small_queue_page()
  IB/ehca: Use default value for Local CA ACK Delay if FW returns 0
  IB/ehca: Filter PATH_MIG events if QP was never armed
  IB/iser: Add support for RDMA_CM_EVENT_ADDR_CHANGE event
  RDMA/cma: Add RDMA_CM_EVENT_TIMEWAIT_EXIT event
  RDMA/cma: Add RDMA_CM_EVENT_ADDR_CHANGE event
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/roland/infiniband:
  MAINTAINERS: Remove Glenn Streiff from NetEffect entry
  mlx4_core: Improve error message when not enough UAR pages are available
  IB/mlx4: Add support for memory management extensions and local DMA L_Key
  IB/mthca: Keep free count for MTT buddy allocator
  mlx4_core: Keep free count for MTT buddy allocator
  mlx4_code: Add missing FW status return code
  IB/mlx4: Rename struct mlx4_lso_seg to mlx4_wqe_lso_seg
  mlx4_core: Add module parameter to enable QoS support
  RDMA/iwcm: Remove IB_ACCESS_LOCAL_WRITE from remote QP attributes
  IPoIB: Include err code in trace message for ib_sa_path_rec_get() failures
  IB/sa_query: Check if sm_ah is NULL in ib_sa_remove_one()
  IB/ehca: Release mutex in error path of alloc_small_queue_page()
  IB/ehca: Use default value for Local CA ACK Delay if FW returns 0
  IB/ehca: Filter PATH_MIG events if QP was never armed
  IB/iser: Add support for RDMA_CM_EVENT_ADDR_CHANGE event
  RDMA/cma: Add RDMA_CM_EVENT_TIMEWAIT_EXIT event
  RDMA/cma: Add RDMA_CM_EVENT_ADDR_CHANGE event
</pre>
</div>
</content>
</entry>
<entry>
<title>PAGE_ALIGN(): correctly handle 64-bit values on 32-bit architectures</title>
<updated>2008-07-24T17:47:21+00:00</updated>
<author>
<name>Andrea Righi</name>
<email>righi.andrea@gmail.com</email>
</author>
<published>2008-07-24T04:28:13+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=27ac792ca0b0a1e7e65f20342260650516c95864'/>
<id>27ac792ca0b0a1e7e65f20342260650516c95864</id>
<content type='text'>
On 32-bit architectures PAGE_ALIGN() truncates 64-bit values to the 32-bit
boundary. For example:

	u64 val = PAGE_ALIGN(size);

always returns a value &lt; 4GB even if size is greater than 4GB.

The problem resides in PAGE_MASK definition (from include/asm-x86/page.h for
example):

#define PAGE_SHIFT      12
#define PAGE_SIZE       (_AC(1,UL) &lt;&lt; PAGE_SHIFT)
#define PAGE_MASK       (~(PAGE_SIZE-1))
...
#define PAGE_ALIGN(addr)       (((addr)+PAGE_SIZE-1)&amp;PAGE_MASK)

The "~" is performed on a 32-bit value, so everything in "and" with
PAGE_MASK greater than 4GB will be truncated to the 32-bit boundary.
Using the ALIGN() macro seems to be the right way, because it uses
typeof(addr) for the mask.

Also move the PAGE_ALIGN() definitions out of include/asm-*/page.h in
include/linux/mm.h.

See also lkml discussion: http://lkml.org/lkml/2008/6/11/237

[akpm@linux-foundation.org: fix drivers/media/video/uvc/uvc_queue.c]
[akpm@linux-foundation.org: fix v850]
[akpm@linux-foundation.org: fix powerpc]
[akpm@linux-foundation.org: fix arm]
[akpm@linux-foundation.org: fix mips]
[akpm@linux-foundation.org: fix drivers/media/video/pvrusb2/pvrusb2-dvb.c]
[akpm@linux-foundation.org: fix drivers/mtd/maps/uclinux.c]
[akpm@linux-foundation.org: fix powerpc]
Signed-off-by: Andrea Righi &lt;righi.andrea@gmail.com&gt;
Cc: &lt;linux-arch@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
On 32-bit architectures PAGE_ALIGN() truncates 64-bit values to the 32-bit
boundary. For example:

	u64 val = PAGE_ALIGN(size);

always returns a value &lt; 4GB even if size is greater than 4GB.

The problem resides in PAGE_MASK definition (from include/asm-x86/page.h for
example):

#define PAGE_SHIFT      12
#define PAGE_SIZE       (_AC(1,UL) &lt;&lt; PAGE_SHIFT)
#define PAGE_MASK       (~(PAGE_SIZE-1))
...
#define PAGE_ALIGN(addr)       (((addr)+PAGE_SIZE-1)&amp;PAGE_MASK)

The "~" is performed on a 32-bit value, so everything in "and" with
PAGE_MASK greater than 4GB will be truncated to the 32-bit boundary.
Using the ALIGN() macro seems to be the right way, because it uses
typeof(addr) for the mask.

Also move the PAGE_ALIGN() definitions out of include/asm-*/page.h in
include/linux/mm.h.

See also lkml discussion: http://lkml.org/lkml/2008/6/11/237

[akpm@linux-foundation.org: fix drivers/media/video/uvc/uvc_queue.c]
[akpm@linux-foundation.org: fix v850]
[akpm@linux-foundation.org: fix powerpc]
[akpm@linux-foundation.org: fix arm]
[akpm@linux-foundation.org: fix mips]
[akpm@linux-foundation.org: fix drivers/media/video/pvrusb2/pvrusb2-dvb.c]
[akpm@linux-foundation.org: fix drivers/mtd/maps/uclinux.c]
[akpm@linux-foundation.org: fix powerpc]
Signed-off-by: Andrea Righi &lt;righi.andrea@gmail.com&gt;
Cc: &lt;linux-arch@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mlx4_core: Improve error message when not enough UAR pages are available</title>
<updated>2008-07-23T15:12:47+00:00</updated>
<author>
<name>Roland Dreier</name>
<email>rolandd@cisco.com</email>
</author>
<published>2008-07-23T15:12:47+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=76442640829163d0cdb67c2bf0cb4b81a0fe537b'/>
<id>76442640829163d0cdb67c2bf0cb4b81a0fe537b</id>
<content type='text'>
If an mlx4 device with default FW (which gives a UAR BAR size of 8 MB)
is used in a system with 64 KB pages, then there are only 8192/64==128
UAR pages available.  However, the first 128 UAR pages are reserved
for use with event queue doorbells, so no UAR pages are available to
do anything else with, which means that the driver cannot work.

The current driver fails with a fairly cryptic "Failed to allocate
driver access region, aborting" message in this situation.  Fix the
driver to detect the problem earlier and print out a clearer
description of the problem and a suggestion of how to fix it (use a
new firmware image).

Signed-off-by: Roland Dreier &lt;rolandd@cisco.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
If an mlx4 device with default FW (which gives a UAR BAR size of 8 MB)
is used in a system with 64 KB pages, then there are only 8192/64==128
UAR pages available.  However, the first 128 UAR pages are reserved
for use with event queue doorbells, so no UAR pages are available to
do anything else with, which means that the driver cannot work.

The current driver fails with a fairly cryptic "Failed to allocate
driver access region, aborting" message in this situation.  Fix the
driver to detect the problem earlier and print out a clearer
description of the problem and a suggestion of how to fix it (use a
new firmware image).

Signed-off-by: Roland Dreier &lt;rolandd@cisco.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>IB/mlx4: Add support for memory management extensions and local DMA L_Key</title>
<updated>2008-07-23T15:12:26+00:00</updated>
<author>
<name>Roland Dreier</name>
<email>rolandd@cisco.com</email>
</author>
<published>2008-07-23T15:12:26+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=95d04f0735b4fc837bff9aedcc3f3efb20ddc3d1'/>
<id>95d04f0735b4fc837bff9aedcc3f3efb20ddc3d1</id>
<content type='text'>
Add support for the following operations to mlx4 when device firmware
supports them:

 - Send with invalidate and local invalidate send queue work requests;
 - Allocate/free fast register MRs;
 - Allocate/free fast register MR page lists;
 - Fast register MR send queue work requests;
 - Local DMA L_Key.

Signed-off-by: Roland Dreier &lt;rolandd@cisco.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Add support for the following operations to mlx4 when device firmware
supports them:

 - Send with invalidate and local invalidate send queue work requests;
 - Allocate/free fast register MRs;
 - Allocate/free fast register MR page lists;
 - Fast register MR send queue work requests;
 - Local DMA L_Key.

Signed-off-by: Roland Dreier &lt;rolandd@cisco.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mlx4_core: Keep free count for MTT buddy allocator</title>
<updated>2008-07-22T21:19:40+00:00</updated>
<author>
<name>Roland Dreier</name>
<email>rolandd@cisco.com</email>
</author>
<published>2008-07-22T21:19:40+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=e4044cfc493338cd09870bd45dc646336bb66e9f'/>
<id>e4044cfc493338cd09870bd45dc646336bb66e9f</id>
<content type='text'>
MTT entries are allocated with a buddy allocator, which just keeps
bitmaps for each level of the buddy table.  However, all free space
starts out at the highest order, and small allocations start scanning
from the lowest order.  When the lowest order tables have no free
space, this can lead to scanning potentially millions of bits before
finding a free entry at a higher order.

We can avoid this by just keeping a count of how many free entries
each order has, and skipping the bitmap scan when an order is
completely empty.  This provides a nice performance boost for a
negligible increase in memory usage.

Signed-off-by: Roland Dreier &lt;rolandd@cisco.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
MTT entries are allocated with a buddy allocator, which just keeps
bitmaps for each level of the buddy table.  However, all free space
starts out at the highest order, and small allocations start scanning
from the lowest order.  When the lowest order tables have no free
space, this can lead to scanning potentially millions of bits before
finding a free entry at a higher order.

We can avoid this by just keeping a count of how many free entries
each order has, and skipping the bitmap scan when an order is
completely empty.  This provides a nice performance boost for a
negligible increase in memory usage.

Signed-off-by: Roland Dreier &lt;rolandd@cisco.com&gt;
</pre>
</div>
</content>
</entry>
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