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Date: Fri, 9 Aug 2013 10:23:35 +0200
From: Alexander Gordeev <agordeev@...hat.com>
To: Tejun Heo <tj@...nel.org>
Cc: "Nicholas A. Bellinger" <nab@...ux-iscsi.org>,
Jens Axboe <axboe@...nel.dk>,
James Bottomley <James.Bottomley@...senPartnership.com>,
Mike Christie <michaelc@...wisc.edu>,
linux-kernel@...r.kernel.org, linux-ide@...r.kernel.org,
Jeff Garzik <jgarzik@...ox.com>,
linux-scsi <linux-scsi@...r.kernel.org>
Subject: Re: [PATCH RESEND 0/1] AHCI: Optimize interrupt processing
On Mon, Jul 29, 2013 at 07:46:53AM -0400, Tejun Heo wrote:
> One thing which would probably be worthwhile tho is getting rid of the
> bitmap based qc tag allocator in libata. That one is just borderline
> stupid to keep around on any setup which is supposed to be scalable.
Hi Tejun,
How about this approach?
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index f218427..5c2a236 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -72,6 +72,8 @@
#include "libata.h"
#include "libata-transport.h"
+#include "../../block/blk-mq-tag.h"
+
/* debounce timing parameters in msecs { interval, duration, timeout } */
const unsigned long sata_deb_timing_normal[] = { 5, 100, 2000 };
const unsigned long sata_deb_timing_hotplug[] = { 25, 500, 2000 };
@@ -1569,18 +1571,8 @@ unsigned ata_exec_internal_sg(struct ata_device *dev,
/* initialize internal qc */
- /* XXX: Tag 0 is used for drivers with legacy EH as some
- * drivers choke if any other tag is given. This breaks
- * ata_tag_internal() test for those drivers. Don't use new
- * EH stuff without converting to it.
- */
- if (ap->ops->error_handler)
- tag = ATA_TAG_INTERNAL;
- else
- tag = 0;
-
- if (test_and_set_bit(tag, &ap->qc_allocated))
- BUG();
+ tag = blk_mq_get_tag(ap->qc_tags, GFP_ATOMIC, true);
+ BUG_ON(!ata_tag_internal(tag));
qc = __ata_qc_from_tag(ap, tag);
qc->tag = tag;
@@ -4733,21 +4725,17 @@ void swap_buf_le16(u16 *buf, unsigned int buf_words)
static struct ata_queued_cmd *ata_qc_new(struct ata_port *ap)
{
struct ata_queued_cmd *qc = NULL;
- unsigned int i;
+ unsigned int tag;
/* no command while frozen */
if (unlikely(ap->pflags & ATA_PFLAG_FROZEN))
return NULL;
- /* the last tag is reserved for internal command. */
- for (i = 0; i < ATA_MAX_QUEUE - 1; i++)
- if (!test_and_set_bit(i, &ap->qc_allocated)) {
- qc = __ata_qc_from_tag(ap, i);
- break;
- }
+ tag = blk_mq_get_tag(ap->qc_tags, GFP_ATOMIC, false);
+ qc = __ata_qc_from_tag(ap, tag);
if (qc)
- qc->tag = i;
+ qc->tag = tag;
return qc;
}
@@ -4799,7 +4787,7 @@ void ata_qc_free(struct ata_queued_cmd *qc)
tag = qc->tag;
if (likely(ata_tag_valid(tag))) {
qc->tag = ATA_TAG_POISON;
- clear_bit(tag, &ap->qc_allocated);
+ blk_mq_put_tag(ap->qc_tags, tag);
}
}
@@ -5639,6 +5627,12 @@ struct ata_port *ata_port_alloc(struct ata_host *host)
if (!ap)
return NULL;
+ ap->qc_tags = blk_mq_init_tags(ATA_MAX_QUEUE, 1, NUMA_NO_NODE);
+ if (!ap->qc_tags) {
+ kfree(ap);
+ return NULL;
+ }
+
ap->pflags |= ATA_PFLAG_INITIALIZING | ATA_PFLAG_FROZEN;
ap->lock = &host->lock;
ap->print_id = -1;
@@ -5677,6 +5671,14 @@ struct ata_port *ata_port_alloc(struct ata_host *host)
return ap;
}
+static void ata_port_free(struct ata_port *ap)
+{
+ kfree(ap->pmp_link);
+ kfree(ap->slave_link);
+ blk_mq_free_tags(ap->qc_tags);
+ kfree(ap);
+}
+
static void ata_host_release(struct device *gendev, void *res)
{
struct ata_host *host = dev_get_drvdata(gendev);
@@ -5691,9 +5693,7 @@ static void ata_host_release(struct device *gendev, void *res)
if (ap->scsi_host)
scsi_host_put(ap->scsi_host);
- kfree(ap->pmp_link);
- kfree(ap->slave_link);
- kfree(ap);
+ ata_port_free(ap);
host->ports[i] = NULL;
}
diff --git a/include/linux/libata.h b/include/linux/libata.h
index eae7a05..4ff9494 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -126,7 +126,7 @@ enum {
ATA_DEF_QUEUE = 1,
/* tag ATA_MAX_QUEUE - 1 is reserved for internal commands */
ATA_MAX_QUEUE = 32,
- ATA_TAG_INTERNAL = ATA_MAX_QUEUE - 1,
+ ATA_TAG_INTERNAL = 0,
ATA_SHORT_PAUSE = 16,
ATAPI_MAX_DRAIN = 16 << 10,
@@ -766,7 +766,7 @@ struct ata_port {
unsigned int cbl; /* cable type; ATA_CBL_xxx */
struct ata_queued_cmd qcmd[ATA_MAX_QUEUE];
- unsigned long qc_allocated;
+ struct blk_mq_tags *qc_tags;
unsigned int qc_active;
int nr_active_links; /* #links with active qcs */
> Thanks.
>
> --
> tejun
--
Regards,
Alexander Gordeev
agordeev@...hat.com
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