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![Ujjal Singh](/assets/img/avatar_default.png)
We observed performance increase with DMA copy from memory to MMIO by changing the interrupt coalescing value to 0. The previous set value was projected on the C5xxx Xeon platform and no longer holds true. Removing hard coded value and providing a tune-able in sysfs in order to allow user to tune this on a per channel basis. By default this value will be set to 0. Example of sysfs variable importing for interrupt coalescing value from command line: echo 5> /sys/devices/pci0000:00/0000:00:04.0/dma/dma0chan0/ quickdata/intr_coalesce Reported-by: Nithin Sujir <nsujir@tintri.com> Signed-off-by: Ujjal Singh <ujjal.singh@intel.com> Acked-by: Dave Jiang <dave.jiang@intel.com> Signed-off-by: Vinod Koul <vinod.koul@intel.com>
177 lines
4.9 KiB
C
177 lines
4.9 KiB
C
/*
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* Intel I/OAT DMA Linux driver
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* Copyright(c) 2004 - 2015 Intel Corporation.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* The full GNU General Public License is included in this distribution in
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* the file called "COPYING".
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*
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*/
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/dmaengine.h>
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#include <linux/pci.h>
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#include "dma.h"
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#include "registers.h"
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#include "hw.h"
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#include "../dmaengine.h"
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static ssize_t cap_show(struct dma_chan *c, char *page)
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{
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struct dma_device *dma = c->device;
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return sprintf(page, "copy%s%s%s%s%s\n",
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dma_has_cap(DMA_PQ, dma->cap_mask) ? " pq" : "",
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dma_has_cap(DMA_PQ_VAL, dma->cap_mask) ? " pq_val" : "",
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dma_has_cap(DMA_XOR, dma->cap_mask) ? " xor" : "",
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dma_has_cap(DMA_XOR_VAL, dma->cap_mask) ? " xor_val" : "",
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dma_has_cap(DMA_INTERRUPT, dma->cap_mask) ? " intr" : "");
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}
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struct ioat_sysfs_entry ioat_cap_attr = __ATTR_RO(cap);
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static ssize_t version_show(struct dma_chan *c, char *page)
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{
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struct dma_device *dma = c->device;
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struct ioatdma_device *ioat_dma = to_ioatdma_device(dma);
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return sprintf(page, "%d.%d\n",
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ioat_dma->version >> 4, ioat_dma->version & 0xf);
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}
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struct ioat_sysfs_entry ioat_version_attr = __ATTR_RO(version);
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static ssize_t
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ioat_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
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{
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struct ioat_sysfs_entry *entry;
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struct ioatdma_chan *ioat_chan;
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entry = container_of(attr, struct ioat_sysfs_entry, attr);
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ioat_chan = container_of(kobj, struct ioatdma_chan, kobj);
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if (!entry->show)
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return -EIO;
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return entry->show(&ioat_chan->dma_chan, page);
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}
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static ssize_t
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ioat_attr_store(struct kobject *kobj, struct attribute *attr,
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const char *page, size_t count)
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{
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struct ioat_sysfs_entry *entry;
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struct ioatdma_chan *ioat_chan;
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entry = container_of(attr, struct ioat_sysfs_entry, attr);
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ioat_chan = container_of(kobj, struct ioatdma_chan, kobj);
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if (!entry->store)
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return -EIO;
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return entry->store(&ioat_chan->dma_chan, page, count);
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}
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const struct sysfs_ops ioat_sysfs_ops = {
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.show = ioat_attr_show,
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.store = ioat_attr_store,
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};
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void ioat_kobject_add(struct ioatdma_device *ioat_dma, struct kobj_type *type)
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{
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struct dma_device *dma = &ioat_dma->dma_dev;
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struct dma_chan *c;
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list_for_each_entry(c, &dma->channels, device_node) {
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struct ioatdma_chan *ioat_chan = to_ioat_chan(c);
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struct kobject *parent = &c->dev->device.kobj;
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int err;
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err = kobject_init_and_add(&ioat_chan->kobj, type,
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parent, "quickdata");
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if (err) {
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dev_warn(to_dev(ioat_chan),
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"sysfs init error (%d), continuing...\n", err);
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kobject_put(&ioat_chan->kobj);
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set_bit(IOAT_KOBJ_INIT_FAIL, &ioat_chan->state);
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}
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}
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}
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void ioat_kobject_del(struct ioatdma_device *ioat_dma)
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{
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struct dma_device *dma = &ioat_dma->dma_dev;
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struct dma_chan *c;
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list_for_each_entry(c, &dma->channels, device_node) {
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struct ioatdma_chan *ioat_chan = to_ioat_chan(c);
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if (!test_bit(IOAT_KOBJ_INIT_FAIL, &ioat_chan->state)) {
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kobject_del(&ioat_chan->kobj);
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kobject_put(&ioat_chan->kobj);
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}
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}
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}
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static ssize_t ring_size_show(struct dma_chan *c, char *page)
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{
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struct ioatdma_chan *ioat_chan = to_ioat_chan(c);
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return sprintf(page, "%d\n", (1 << ioat_chan->alloc_order) & ~1);
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}
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static struct ioat_sysfs_entry ring_size_attr = __ATTR_RO(ring_size);
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static ssize_t ring_active_show(struct dma_chan *c, char *page)
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{
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struct ioatdma_chan *ioat_chan = to_ioat_chan(c);
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/* ...taken outside the lock, no need to be precise */
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return sprintf(page, "%d\n", ioat_ring_active(ioat_chan));
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}
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static struct ioat_sysfs_entry ring_active_attr = __ATTR_RO(ring_active);
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static ssize_t intr_coalesce_show(struct dma_chan *c, char *page)
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{
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struct ioatdma_chan *ioat_chan = to_ioat_chan(c);
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return sprintf(page, "%d\n", ioat_chan->intr_coalesce);
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}
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static ssize_t intr_coalesce_store(struct dma_chan *c, const char *page,
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size_t count)
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{
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int intr_coalesce = 0;
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struct ioatdma_chan *ioat_chan = to_ioat_chan(c);
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if (sscanf(page, "%du", &intr_coalesce) != -1) {
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if ((intr_coalesce < 0) ||
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(intr_coalesce > IOAT_INTRDELAY_MASK))
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return -EINVAL;
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ioat_chan->intr_coalesce = intr_coalesce;
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}
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return count;
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}
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static struct ioat_sysfs_entry intr_coalesce_attr = __ATTR_RW(intr_coalesce);
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static struct attribute *ioat_attrs[] = {
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&ring_size_attr.attr,
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&ring_active_attr.attr,
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&ioat_cap_attr.attr,
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&ioat_version_attr.attr,
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&intr_coalesce_attr.attr,
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NULL,
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};
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struct kobj_type ioat_ktype = {
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.sysfs_ops = &ioat_sysfs_ops,
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.default_attrs = ioat_attrs,
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};
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