[PATCH 0/9] I/OAT fixes

[PATCH 0/9] I/OAT fixes

[Chris Leech]

Andrew Morton (1):
     I/OAT: warning fix

Chris Leech (6):
     ioatdma: Push pending transactions to hardware more frequently
     ioatdma: Remove the wrappers around read(bwl)/write(bwl) in ioatdma
     ioatdma: Remove the use of writeq from the ioatdma driver
     I/OAT: Add documentation for the tcp_dma_copybreak sysctl
     I/OAT: Add entries to MAINTAINERS for the DMA memcpy subsystem and ioatdma
     I/OAT: Only offload copies for TCP when there will be a context switch

Dan Aloni (1):
     I/OAT: fix I/OAT for kexec

Jeff Garzik (1):
     drivers/dma: handle sysfs errors

 Documentation/networking/ip-sysctl.txt |    6 +
 MAINTAINERS                            |   12 +++
 drivers/dma/dmaengine.c                |   22 +++++-
 drivers/dma/ioatdma.c                  |   81 ++++++++++++----------
 drivers/dma/ioatdma_io.h               |  118 ---------------------------------
 net/ipv4/tcp.c                         |   26 +++++--
 6 files changed, 100 insertions(+), 165 deletions(-)

--
Chris Leech <christopher.leech@intel.com>
I/O Acceleration Technology Software Development
LAN Access Division / Digital Enterprise Group 

[PATCH 1/9] ioatdma: Push pending transactions to hardware more frequently

[Chris Leech]

Every 20 descriptors turns out to be to few append commands with
newer/faster CPUs.  Pushing every 4 still cuts down on MMIO writes to an
acceptable level without letting the DMA engine run out of work.

Signed-off-by: Chris Leech <christopher.leech@intel.com>
---

 drivers/dma/ioatdma.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/ioatdma.c b/drivers/dma/ioatdma.c
index 8e87261..0f77a9d 100644
--- a/drivers/dma/ioatdma.c
+++ b/drivers/dma/ioatdma.c
@@ -310,7 +310,7 @@ static dma_cookie_t do_ioat_dma_memcpy(struct ioat_dma_chan *ioat_chan,
 	list_splice_init(&new_chain, ioat_chan->used_desc.prev);
 
 	ioat_chan->pending += desc_count;
-	if (ioat_chan->pending >= 20) {
+	if (ioat_chan->pending >= 4) {
 		append = 1;
 		ioat_chan->pending = 0;
 	}
@@ -818,7 +818,7 @@ static void __devexit ioat_remove(struct pci_dev *pdev)
 }
 
 /* MODULE API */
-MODULE_VERSION("1.7");
+MODULE_VERSION("1.9");
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Intel Corporation");
 

Re: [PATCH 1/9] ioatdma: Push pending transactions to hardware more frequently

[Jeff Garzik]

Chris Leech wrote:
> Every 20 descriptors turns out to be to few append commands with
> newer/faster CPUs.  Pushing every 4 still cuts down on MMIO writes to an
> acceptable level without letting the DMA engine run out of work.
> 
> Signed-off-by: Chris Leech <christopher.leech@intel.com>
> ---
> 
>  drivers/dma/ioatdma.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/dma/ioatdma.c b/drivers/dma/ioatdma.c
> index 8e87261..0f77a9d 100644
> --- a/drivers/dma/ioatdma.c
> +++ b/drivers/dma/ioatdma.c
> @@ -310,7 +310,7 @@ static dma_cookie_t do_ioat_dma_memcpy(struct ioat_dma_chan *ioat_chan,
>  	list_splice_init(&new_chain, ioat_chan->used_desc.prev);
>  
>  	ioat_chan->pending += desc_count;
> -	if (ioat_chan->pending >= 20) {
> +	if (ioat_chan->pending >= 4) {

This sounds like something that will always be wrong -- or in other 
words, always be right for only the latest CPUs.  Can this be made 
dynamic, based on some timing factor?

	Jeff

Re: [PATCH 1/9] ioatdma: Push pending transactions to hardware more frequently

[David Miller]

From: Jeff Garzik <jeff@garzik.org>
Date: Fri, 02 Mar 2007 22:14:39 -0500

> Chris Leech wrote:
> > Every 20 descriptors turns out to be to few append commands with
> > newer/faster CPUs.  Pushing every 4 still cuts down on MMIO writes to an
> > acceptable level without letting the DMA engine run out of work.
> > 
> > Signed-off-by: Chris Leech <christopher.leech@intel.com>
> > ---
> > 
> >  drivers/dma/ioatdma.c |    4 ++--
> >  1 files changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/dma/ioatdma.c b/drivers/dma/ioatdma.c
> > index 8e87261..0f77a9d 100644
> > --- a/drivers/dma/ioatdma.c
> > +++ b/drivers/dma/ioatdma.c
> > @@ -310,7 +310,7 @@ static dma_cookie_t do_ioat_dma_memcpy(struct ioat_dma_chan *ioat_chan,
> >  	list_splice_init(&new_chain, ioat_chan->used_desc.prev);
> >  
> >  	ioat_chan->pending += desc_count;
> > -	if (ioat_chan->pending >= 20) {
> > +	if (ioat_chan->pending >= 4) {
> 
> This sounds like something that will always be wrong -- or in other 
> words, always be right for only the latest CPUs.  Can this be made 
> dynamic, based on some timing factor?

In fact I think this has been tweaked twice in the vanilla tree
already.

Re: [PATCH 1/9] ioatdma: Push pending transactions to hardware more frequently

[Chris Leech]

> > This sounds like something that will always be wrong -- or in other
> > words, always be right for only the latest CPUs.  Can this be made
> > dynamic, based on some timing factor?
>
> In fact I think this has been tweaked twice in the vanilla tree
> already.

This is actually just the same tweak you remember me posting before
and I never pushed to get it in mainline, but Jeff's right.  The
problem isn't so much in the driver itself, as in how it's used by
I/OAT in the TCP receive code, there are inherent assumptions about
how long a context switch takes compared to how long an offloaded
memcpy takes.

I'm working on using completion interrupts for the device so as not to
end up polling when the CPUs are faster than the code was tuned for,
and doing it in a way that doesn't introduce extra context switches.
I'm hoping to have something ready for 2.6.22, or at least ready for
MM in that time frame.

As for this change in the short term, we did go back and make sure
that it didn't performance worse with the older CPUs supported on
these platforms.  We should have tested more intermediate values
instead of just jumping from 1 t o 20 for that threshold.

- Chris

[PATCH 2/9] drivers/dma: handle sysfs errors

[Chris Leech]

From: Jeff Garzik <jeff@garzik.org>

Signed-off-by: Jeff Garzik <jeff@garzik.org>
Signed-off-by: Chris Leech <christopher.leech@intel.com>
---

 drivers/dma/dmaengine.c |   22 ++++++++++++++++++++--
 1 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index 1527804..dc65773 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -312,7 +312,7 @@ void dma_async_client_chan_request(struct dma_client *client,
 int dma_async_device_register(struct dma_device *device)
 {
 	static int id;
-	int chancnt = 0;
+	int chancnt = 0, rc;
 	struct dma_chan* chan;
 
 	if (!device)
@@ -334,8 +334,15 @@ int dma_async_device_register(struct dma_device *device)
 		snprintf(chan->class_dev.class_id, BUS_ID_SIZE, "dma%dchan%d",
 		         device->dev_id, chan->chan_id);
 
+		rc = class_device_register(&chan->class_dev);
+		if (rc) {
+			chancnt--;
+			free_percpu(chan->local);
+			chan->local = NULL;
+			goto err_out;
+		}
+
 		kref_get(&device->refcount);
-		class_device_register(&chan->class_dev);
 	}
 
 	mutex_lock(&dma_list_mutex);
@@ -345,6 +352,17 @@ int dma_async_device_register(struct dma_device *device)
 	dma_chans_rebalance();
 
 	return 0;
+
+err_out:
+	list_for_each_entry(chan, &device->channels, device_node) {
+		if (chan->local == NULL)
+			continue;
+		kref_put(&device->refcount, dma_async_device_cleanup);
+		class_device_unregister(&chan->class_dev);
+		chancnt--;
+		free_percpu(chan->local);
+	}
+	return rc;
 }
 
 /**

[PATCH 3/9] ioatdma: Remove the wrappers around read(bwl)/write(bwl) in ioatdma

[Chris Leech]

Signed-off-by: Chris Leech <christopher.leech@intel.com>
---

 drivers/dma/ioatdma.c    |   60 +++++++++++------------
 drivers/dma/ioatdma_io.h |  118 ----------------------------------------------
 2 files changed, 28 insertions(+), 150 deletions(-)

diff --git a/drivers/dma/ioatdma.c b/drivers/dma/ioatdma.c
index 0f77a9d..ec11131 100644
--- a/drivers/dma/ioatdma.c
+++ b/drivers/dma/ioatdma.c
@@ -32,7 +32,6 @@
 #include <linux/delay.h>
 #include <linux/dma-mapping.h>
 #include "ioatdma.h"
-#include "ioatdma_io.h"
 #include "ioatdma_registers.h"
 #include "ioatdma_hw.h"
 
@@ -51,8 +50,8 @@ static int enumerate_dma_channels(struct ioat_device *device)
 	int i;
 	struct ioat_dma_chan *ioat_chan;
 
-	device->common.chancnt = ioatdma_read8(device, IOAT_CHANCNT_OFFSET);
-	xfercap_scale = ioatdma_read8(device, IOAT_XFERCAP_OFFSET);
+	device->common.chancnt = readb(device->reg_base + IOAT_CHANCNT_OFFSET);
+	xfercap_scale = readb(device->reg_base + IOAT_XFERCAP_OFFSET);
 	xfercap = (xfercap_scale == 0 ? -1 : (1UL << xfercap_scale));
 
 	for (i = 0; i < device->common.chancnt; i++) {
@@ -123,7 +122,7 @@ static int ioat_dma_alloc_chan_resources(struct dma_chan *chan)
 	 * In-use bit automatically set by reading chanctrl
 	 * If 0, we got it, if 1, someone else did
 	 */
-	chanctrl = ioatdma_chan_read16(ioat_chan, IOAT_CHANCTRL_OFFSET);
+	chanctrl = readw(ioat_chan->reg_base + IOAT_CHANCTRL_OFFSET);
 	if (chanctrl & IOAT_CHANCTRL_CHANNEL_IN_USE)
 		return -EBUSY;
 
@@ -132,12 +131,12 @@ static int ioat_dma_alloc_chan_resources(struct dma_chan *chan)
 		IOAT_CHANCTRL_ERR_INT_EN |
 		IOAT_CHANCTRL_ANY_ERR_ABORT_EN |
 		IOAT_CHANCTRL_ERR_COMPLETION_EN;
-        ioatdma_chan_write16(ioat_chan, IOAT_CHANCTRL_OFFSET, chanctrl);
+        writew(chanctrl, ioat_chan->reg_base + IOAT_CHANCTRL_OFFSET);
 
-	chanerr = ioatdma_chan_read32(ioat_chan, IOAT_CHANERR_OFFSET);
+	chanerr = readl(ioat_chan->reg_base + IOAT_CHANERR_OFFSET);
 	if (chanerr) {
 		printk("IOAT: CHANERR = %x, clearing\n", chanerr);
-		ioatdma_chan_write32(ioat_chan, IOAT_CHANERR_OFFSET, chanerr);
+		writel(chanerr, ioat_chan->reg_base + IOAT_CHANERR_OFFSET);
 	}
 
 	/* Allocate descriptors */
@@ -161,10 +160,10 @@ static int ioat_dma_alloc_chan_resources(struct dma_chan *chan)
 		               &ioat_chan->completion_addr);
 	memset(ioat_chan->completion_virt, 0,
 	       sizeof(*ioat_chan->completion_virt));
-	ioatdma_chan_write32(ioat_chan, IOAT_CHANCMP_OFFSET_LOW,
-	               ((u64) ioat_chan->completion_addr) & 0x00000000FFFFFFFF);
-	ioatdma_chan_write32(ioat_chan, IOAT_CHANCMP_OFFSET_HIGH,
-	               ((u64) ioat_chan->completion_addr) >> 32);
+	writel(((u64) ioat_chan->completion_addr) & 0x00000000FFFFFFFF,
+	       ioat_chan->reg_base + IOAT_CHANCMP_OFFSET_LOW);
+	writel(((u64) ioat_chan->completion_addr) >> 32,
+	       ioat_chan->reg_base + IOAT_CHANCMP_OFFSET_HIGH);
 
 	ioat_start_null_desc(ioat_chan);
 	return i;
@@ -182,7 +181,7 @@ static void ioat_dma_free_chan_resources(struct dma_chan *chan)
 
 	ioat_dma_memcpy_cleanup(ioat_chan);
 
-	ioatdma_chan_write8(ioat_chan, IOAT_CHANCMD_OFFSET, IOAT_CHANCMD_RESET);
+	writeb(IOAT_CHANCMD_RESET, ioat_chan->reg_base + IOAT_CHANCMD_OFFSET);
 
 	spin_lock_bh(&ioat_chan->desc_lock);
 	list_for_each_entry_safe(desc, _desc, &ioat_chan->used_desc, node) {
@@ -210,9 +209,9 @@ static void ioat_dma_free_chan_resources(struct dma_chan *chan)
 	ioat_chan->last_completion = ioat_chan->completion_addr = 0;
 
 	/* Tell hw the chan is free */
-	chanctrl = ioatdma_chan_read16(ioat_chan, IOAT_CHANCTRL_OFFSET);
+	chanctrl = readw(ioat_chan->reg_base + IOAT_CHANCTRL_OFFSET);
 	chanctrl &= ~IOAT_CHANCTRL_CHANNEL_IN_USE;
-	ioatdma_chan_write16(ioat_chan, IOAT_CHANCTRL_OFFSET, chanctrl);
+	writew(chanctrl, ioat_chan->reg_base + IOAT_CHANCTRL_OFFSET);
 }
 
 /**
@@ -318,9 +317,8 @@ static dma_cookie_t do_ioat_dma_memcpy(struct ioat_dma_chan *ioat_chan,
 	spin_unlock_bh(&ioat_chan->desc_lock);
 
 	if (append)
-		ioatdma_chan_write8(ioat_chan,
-		                    IOAT_CHANCMD_OFFSET,
-		                    IOAT_CHANCMD_APPEND);
+		writeb(IOAT_CHANCMD_APPEND,
+		       ioat_chan->reg_base + IOAT_CHANCMD_OFFSET);
 	return cookie;
 }
 
@@ -417,9 +415,8 @@ static void ioat_dma_memcpy_issue_pending(struct dma_chan *chan)
 
 	if (ioat_chan->pending != 0) {
 		ioat_chan->pending = 0;
-		ioatdma_chan_write8(ioat_chan,
-		                    IOAT_CHANCMD_OFFSET,
-		                    IOAT_CHANCMD_APPEND);
+		writeb(IOAT_CHANCMD_APPEND,
+		       ioat_chan->reg_base + IOAT_CHANCMD_OFFSET);
 	}
 }
 
@@ -449,7 +446,7 @@ static void ioat_dma_memcpy_cleanup(struct ioat_dma_chan *chan)
 	if ((chan->completion_virt->full & IOAT_CHANSTS_DMA_TRANSFER_STATUS) ==
 		IOAT_CHANSTS_DMA_TRANSFER_STATUS_HALTED) {
 		printk("IOAT: Channel halted, chanerr = %x\n",
-			ioatdma_chan_read32(chan, IOAT_CHANERR_OFFSET));
+			readl(chan->reg_base + IOAT_CHANERR_OFFSET));
 
 		/* TODO do something to salvage the situation */
 	}
@@ -569,21 +566,21 @@ static irqreturn_t ioat_do_interrupt(int irq, void *data)
 	unsigned long attnstatus;
 	u8 intrctrl;
 
-	intrctrl = ioatdma_read8(instance, IOAT_INTRCTRL_OFFSET);
+	intrctrl = readb(instance->reg_base + IOAT_INTRCTRL_OFFSET);
 
 	if (!(intrctrl & IOAT_INTRCTRL_MASTER_INT_EN))
 		return IRQ_NONE;
 
 	if (!(intrctrl & IOAT_INTRCTRL_INT_STATUS)) {
-		ioatdma_write8(instance, IOAT_INTRCTRL_OFFSET, intrctrl);
+		writeb(intrctrl, instance->reg_base + IOAT_INTRCTRL_OFFSET);
 		return IRQ_NONE;
 	}
 
-	attnstatus = ioatdma_read32(instance, IOAT_ATTNSTATUS_OFFSET);
+	attnstatus = readl(instance->reg_base + IOAT_ATTNSTATUS_OFFSET);
 
 	printk(KERN_ERR "ioatdma error: interrupt! status %lx\n", attnstatus);
 
-	ioatdma_write8(instance, IOAT_INTRCTRL_OFFSET, intrctrl);
+	writeb(intrctrl, instance->reg_base + IOAT_INTRCTRL_OFFSET);
 	return IRQ_HANDLED;
 }
 
@@ -612,14 +609,13 @@ static void ioat_start_null_desc(struct ioat_dma_chan *ioat_chan)
 	spin_unlock_bh(&ioat_chan->desc_lock);
 
 #if (BITS_PER_LONG == 64)
-	ioatdma_chan_write64(ioat_chan, IOAT_CHAINADDR_OFFSET, desc->phys);
+	writeq(desc->phys, ioat_chan->reg_base + IOAT_CHAINADDR_OFFSET);
 #else
-	ioatdma_chan_write32(ioat_chan,
-	                     IOAT_CHAINADDR_OFFSET_LOW,
-	                     (u32) desc->phys);
-	ioatdma_chan_write32(ioat_chan, IOAT_CHAINADDR_OFFSET_HIGH, 0);
+	writel((u32) desc->phys,
+	       ioat_chan->reg_base + IOAT_CHAINADDR_OFFSET_LOW);
+	writel(0, ioat_chan->reg_base + IOAT_CHAINADDR_OFFSET_HIGH);
 #endif
-	ioatdma_chan_write8(ioat_chan, IOAT_CHANCMD_OFFSET, IOAT_CHANCMD_START);
+	writeb(IOAT_CHANCMD_START, ioat_chan->reg_base + IOAT_CHANCMD_OFFSET);
 }
 
 /*
@@ -748,7 +744,7 @@ static int __devinit ioat_probe(struct pci_dev *pdev,
 
 	device->reg_base = reg_base;
 
-	ioatdma_write8(device, IOAT_INTRCTRL_OFFSET, IOAT_INTRCTRL_MASTER_INT_EN);
+	writeb(IOAT_INTRCTRL_MASTER_INT_EN, device->reg_base + IOAT_INTRCTRL_OFFSET);
 	pci_set_master(pdev);
 
 	INIT_LIST_HEAD(&device->common.channels);
diff --git a/drivers/dma/ioatdma_io.h b/drivers/dma/ioatdma_io.h
deleted file mode 100644
index c0b4bf6..0000000
--- a/drivers/dma/ioatdma_io.h
+++ /dev/null
@@ -1,118 +0,0 @@
-/*
- * Copyright(c) 2004 - 2006 Intel Corporation. All rights reserved.
- *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License as published by the Free
- * Software Foundation; either version 2 of the License, or (at your option)
- * any later version.
- *
- * This program is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
- * more details.
- *
- * You should have received a copy of the GNU General Public License along with
- * this program; if not, write to the Free Software Foundation, Inc., 59
- * Temple Place - Suite 330, Boston, MA  02111-1307, USA.
- *
- * The full GNU General Public License is included in this distribution in the
- * file called COPYING.
- */
-#ifndef IOATDMA_IO_H
-#define IOATDMA_IO_H
-
-#include <asm/io.h>
-
-/*
- * device and per-channel MMIO register read and write functions
- * this is a lot of anoying inline functions, but it's typesafe
- */
-
-static inline u8 ioatdma_read8(struct ioat_device *device,
-                               unsigned int offset)
-{
-	return readb(device->reg_base + offset);
-}
-
-static inline u16 ioatdma_read16(struct ioat_device *device,
-                                 unsigned int offset)
-{
-	return readw(device->reg_base + offset);
-}
-
-static inline u32 ioatdma_read32(struct ioat_device *device,
-                                 unsigned int offset)
-{
-	return readl(device->reg_base + offset);
-}
-
-static inline void ioatdma_write8(struct ioat_device *device,
-                                  unsigned int offset, u8 value)
-{
-	writeb(value, device->reg_base + offset);
-}
-
-static inline void ioatdma_write16(struct ioat_device *device,
-                                   unsigned int offset, u16 value)
-{
-	writew(value, device->reg_base + offset);
-}
-
-static inline void ioatdma_write32(struct ioat_device *device,
-                                   unsigned int offset, u32 value)
-{
-	writel(value, device->reg_base + offset);
-}
-
-static inline u8 ioatdma_chan_read8(struct ioat_dma_chan *chan,
-                                    unsigned int offset)
-{
-	return readb(chan->reg_base + offset);
-}
-
-static inline u16 ioatdma_chan_read16(struct ioat_dma_chan *chan,
-                                      unsigned int offset)
-{
-	return readw(chan->reg_base + offset);
-}
-
-static inline u32 ioatdma_chan_read32(struct ioat_dma_chan *chan,
-                                      unsigned int offset)
-{
-	return readl(chan->reg_base + offset);
-}
-
-static inline void ioatdma_chan_write8(struct ioat_dma_chan *chan,
-                                       unsigned int offset, u8 value)
-{
-	writeb(value, chan->reg_base + offset);
-}
-
-static inline void ioatdma_chan_write16(struct ioat_dma_chan *chan,
-                                        unsigned int offset, u16 value)
-{
-	writew(value, chan->reg_base + offset);
-}
-
-static inline void ioatdma_chan_write32(struct ioat_dma_chan *chan,
-                                        unsigned int offset, u32 value)
-{
-	writel(value, chan->reg_base + offset);
-}
-
-#if (BITS_PER_LONG == 64)
-static inline u64 ioatdma_chan_read64(struct ioat_dma_chan *chan,
-                                      unsigned int offset)
-{
-	return readq(chan->reg_base + offset);
-}
-
-static inline void ioatdma_chan_write64(struct ioat_dma_chan *chan,
-                                        unsigned int offset, u64 value)
-{
-	writeq(value, chan->reg_base + offset);
-}
-#endif
-
-#endif /* IOATDMA_IO_H */
-

[PATCH 4/9] ioatdma: Remove the use of writeq from the ioatdma driver

[Chris Leech]

There's only one now anyway, and it's not in a performance path,
so make it behave the same on 32-bit and 64-bit CPUs.

Signed-off-by: Chris Leech <christopher.leech@intel.com>
---

 drivers/dma/ioatdma.c |   10 ++++------
 1 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/dma/ioatdma.c b/drivers/dma/ioatdma.c
index ec11131..cbf93ca 100644
--- a/drivers/dma/ioatdma.c
+++ b/drivers/dma/ioatdma.c
@@ -608,13 +608,11 @@ static void ioat_start_null_desc(struct ioat_dma_chan *ioat_chan)
 	list_add_tail(&desc->node, &ioat_chan->used_desc);
 	spin_unlock_bh(&ioat_chan->desc_lock);
 
-#if (BITS_PER_LONG == 64)
-	writeq(desc->phys, ioat_chan->reg_base + IOAT_CHAINADDR_OFFSET);
-#else
-	writel((u32) desc->phys,
+	writel(((u64) desc->phys) & 0x00000000FFFFFFFF,
 	       ioat_chan->reg_base + IOAT_CHAINADDR_OFFSET_LOW);
-	writel(0, ioat_chan->reg_base + IOAT_CHAINADDR_OFFSET_HIGH);
-#endif
+	writel(((u64) desc->phys) >> 32,
+	       ioat_chan->reg_base + IOAT_CHAINADDR_OFFSET_HIGH);
+
 	writeb(IOAT_CHANCMD_START, ioat_chan->reg_base + IOAT_CHANCMD_OFFSET);
 }
 

[PATCH 5/9] I/OAT: Add documentation for the tcp_dma_copybreak sysctl

[Chris Leech]

Signed-off-by: Chris Leech <christopher.leech@intel.com>
---

 Documentation/networking/ip-sysctl.txt |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index d3aae1f..9541691 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -413,6 +413,12 @@ tcp_workaround_signed_windows - BOOLEAN
 	not receive a window scaling option from them.
 	Default: 0
 
+tcp_dma_copybreak - INTEGER
+	Lower limit, in bytes, of the size of socket reads that will be
+	offloaded to a DMA copy engine, if one is present in the system
+	and CONFIG_NET_DMA is enabled.
+	Default: 4096
+
 CIPSOv4 Variables:
 
 cipso_cache_enable - BOOLEAN

[PATCH 6/9] I/OAT: Add entries to MAINTAINERS for the DMA memcpy subsystem and ioatdma

[Chris Leech]

Signed-off-by: Chris Leech <christopher.leech@intel.com>
---

 MAINTAINERS |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)

diff --git a/MAINTAINERS b/MAINTAINERS
index 1dfba85..2dd5d23 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1156,6 +1156,12 @@ M:	tori@unhappy.mine.nu
 L:	netdev@vger.kernel.org
 S:	Maintained
 
+DMA GENERIC MEMCPY SUBSYSTEM
+P:	Chris Leech
+M:	christopher.leech@intel.com
+L:	linux-kernel@vger.kernel.org
+S:	Maintained
+
 DOCBOOK FOR DOCUMENTATION
 P:	Randy Dunlap
 M:	rdunlap@xenotime.net
@@ -1777,6 +1783,12 @@ P:	Tigran Aivazian
 M:	tigran@aivazian.fsnet.co.uk
 S:	Maintained
 
+INTEL I/OAT DMA DRIVER
+P:	Chris Leech
+M:	christopher.leech@intel.com
+L:	linux-kernel@vger.kernel.org
+S:	Supported
+
 INTEL IXP4XX RANDOM NUMBER GENERATOR SUPPORT
 P:	Deepak Saxena
 M:	dsaxena@plexity.net

[PATCH 7/9] I/OAT: Only offload copies for TCP when there will be a context switch

[Chris Leech]

The performance wins come with having the DMA copy engine doing the copies
in parallel with the context switch.  If there is enough data ready on the
socket at recv time just use a regular copy.

Signed-off-by: Chris Leech <christopher.leech@intel.com>
---

 net/ipv4/tcp.c |   10 +++++++---
 1 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 74c4d10..5ccd5e1 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1110,6 +1110,8 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 	long timeo;
 	struct task_struct *user_recv = NULL;
 	int copied_early = 0;
+	int available = 0;
+	struct sk_buff *skb;
 
 	lock_sock(sk);
 
@@ -1136,7 +1138,11 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 #ifdef CONFIG_NET_DMA
 	tp->ucopy.dma_chan = NULL;
 	preempt_disable();
-	if ((len > sysctl_tcp_dma_copybreak) && !(flags & MSG_PEEK) &&
+	skb = skb_peek_tail(&sk->sk_receive_queue);
+	if (skb)
+		available = TCP_SKB_CB(skb)->seq + skb->len - (*seq);
+	if ((available < target) &&
+	    (len > sysctl_tcp_dma_copybreak) && !(flags & MSG_PEEK) &&
 	    !sysctl_tcp_low_latency && __get_cpu_var(softnet_data).net_dma) {
 		preempt_enable_no_resched();
 		tp->ucopy.pinned_list = dma_pin_iovec_pages(msg->msg_iov, len);
@@ -1145,7 +1151,6 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 #endif
 
 	do {
-		struct sk_buff *skb;
 		u32 offset;
 
 		/* Are we at urgent data? Stop if we have read anything or have SIGURG pending. */
@@ -1433,7 +1438,6 @@ skip_copy:
 
 #ifdef CONFIG_NET_DMA
 	if (tp->ucopy.dma_chan) {
-		struct sk_buff *skb;
 		dma_cookie_t done, used;
 
 		dma_async_memcpy_issue_pending(tp->ucopy.dma_chan);

[PATCH 8/9] I/OAT: warning fix

[Chris Leech]

net/ipv4/tcp.c: In function 'tcp_recvmsg':
net/ipv4/tcp.c:1111: warning: unused variable 'available'

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Chris Leech <christopher.leech@intel.com>
---

 net/ipv4/tcp.c |   26 ++++++++++++++++----------
 1 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 5ccd5e1..69c525d 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1110,7 +1110,6 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 	long timeo;
 	struct task_struct *user_recv = NULL;
 	int copied_early = 0;
-	int available = 0;
 	struct sk_buff *skb;
 
 	lock_sock(sk);
@@ -1139,15 +1138,22 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 	tp->ucopy.dma_chan = NULL;
 	preempt_disable();
 	skb = skb_peek_tail(&sk->sk_receive_queue);
-	if (skb)
-		available = TCP_SKB_CB(skb)->seq + skb->len - (*seq);
-	if ((available < target) &&
-	    (len > sysctl_tcp_dma_copybreak) && !(flags & MSG_PEEK) &&
-	    !sysctl_tcp_low_latency && __get_cpu_var(softnet_data).net_dma) {
-		preempt_enable_no_resched();
-		tp->ucopy.pinned_list = dma_pin_iovec_pages(msg->msg_iov, len);
-	} else
-		preempt_enable_no_resched();
+	{
+		int available = 0;
+
+		if (skb)
+			available = TCP_SKB_CB(skb)->seq + skb->len - (*seq);
+		if ((available < target) &&
+		    (len > sysctl_tcp_dma_copybreak) && !(flags & MSG_PEEK) &&
+		    !sysctl_tcp_low_latency &&
+		    __get_cpu_var(softnet_data).net_dma) {
+			preempt_enable_no_resched();
+			tp->ucopy.pinned_list =
+					dma_pin_iovec_pages(msg->msg_iov, len);
+		} else {
+			preempt_enable_no_resched();
+		}
+	}
 #endif
 
 	do {

[PATCH 9/9] I/OAT: fix I/OAT for kexec

[Chris Leech]

Under kexec, I/OAT initialization breaks over busy resources because the
previous kernel did not release them.

I'm not sure this fix can be considered a complete one but it works for me.
 I guess something similar to the *_remove method should occur there..

Signed-off-by: Dan Aloni <da-x@monatomic.org>
Signed-off-by: Chris Leech <christopher.leech@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/dma/ioatdma.c |   13 +++++++++++++
 1 files changed, 13 insertions(+), 0 deletions(-)

diff --git a/drivers/dma/ioatdma.c b/drivers/dma/ioatdma.c
index cbf93ca..1d259e5 100644
--- a/drivers/dma/ioatdma.c
+++ b/drivers/dma/ioatdma.c
@@ -41,6 +41,7 @@
 
 /* internal functions */
 static int __devinit ioat_probe(struct pci_dev *pdev, const struct pci_device_id *ent);
+static void ioat_shutdown(struct pci_dev *pdev);
 static void __devexit ioat_remove(struct pci_dev *pdev);
 
 static int enumerate_dma_channels(struct ioat_device *device)
@@ -557,6 +558,7 @@ static struct pci_driver ioat_pci_drv = {
 	.name 	= "ioatdma",
 	.id_table = ioat_pci_tbl,
 	.probe	= ioat_probe,
+	.shutdown = ioat_shutdown,
 	.remove	= __devexit_p(ioat_remove),
 };
 
@@ -781,9 +783,20 @@ err_request_regions:
 err_set_dma_mask:
 	pci_disable_device(pdev);
 err_enable_device:
+
+	printk(KERN_ERR "Intel(R) I/OAT DMA Engine initialization failed\n");
+
 	return err;
 }
 
+static void ioat_shutdown(struct pci_dev *pdev)
+{
+	struct ioat_device *device;
+	device = pci_get_drvdata(pdev);
+
+	dma_async_device_unregister(&device->common);
+}
+
 static void __devexit ioat_remove(struct pci_dev *pdev)
 {
 	struct ioat_device *device;