From: Greg KH <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org,
alan@lxorguk.ukuu.org.uk,
Bernd Schubert <bernd.schubert@itwm.fraunhofer.de>,
Junichi Nomura <j-nomura@ce.jp.nec.com>,
James Bottomley <JBottomley@Parallels.com>
Subject: [ 02/47] SCSI: Fix dm-multipath starvation when scsi host is busy
Date: Thu, 07 Jun 2012 13:14:00 +0900 [thread overview]
Message-ID: <20120607041358.482356043@linuxfoundation.org> (raw)
In-Reply-To: <20120607041504.GA13819@kroah.com>
3.0-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
commit b7e94a1686c5daef4f649f7f4f839cc294f07710 upstream.
block congestion control doesn't have any concept of fairness across
multiple queues. This means that if SCSI reports the host as busy in
the queue congestion control it can result in an unfair starvation
situation in dm-mp if there are multiple multipath devices on the same
host. For example:
http://www.redhat.com/archives/dm-devel/2012-May/msg00123.html
The fix for this is to report only the sdev busy state (and ignore the
host busy state) in the block congestion control call back.
The host is still congested, but the SCSI subsystem will sort out the
congestion in a fair way because it knows the relation between the
queues and the host.
[jejb: fixed up trailing whitespace]
Reported-by: Bernd Schubert <bernd.schubert@itwm.fraunhofer.de>
Tested-by: Bernd Schubert <bernd.schubert@itwm.fraunhofer.de>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/scsi/scsi_lib.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1380,16 +1380,19 @@ static int scsi_lld_busy(struct request_
{
struct scsi_device *sdev = q->queuedata;
struct Scsi_Host *shost;
- struct scsi_target *starget;
if (!sdev)
return 0;
shost = sdev->host;
- starget = scsi_target(sdev);
- if (scsi_host_in_recovery(shost) || scsi_host_is_busy(shost) ||
- scsi_target_is_busy(starget) || scsi_device_is_busy(sdev))
+ /*
+ * Ignore host/starget busy state.
+ * Since block layer does not have a concept of fairness across
+ * multiple queues, congestion of host/starget needs to be handled
+ * in SCSI layer.
+ */
+ if (scsi_host_in_recovery(shost) || scsi_device_is_busy(sdev))
return 1;
return 0;
next prev parent reply other threads:[~2012-06-07 4:14 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-07 4:15 [ 00/47] 3.0.34-stable review Greg KH
2012-06-07 4:13 ` [ 01/47] SCSI: fix scsi_wait_scan Greg KH
2012-06-07 4:14 ` Greg KH [this message]
2012-06-07 4:14 ` [ 03/47] mm: consider all swapped back pages in used-once logic Greg KH
2012-06-07 4:14 ` [ 04/47] mm: pmd_read_atomic: fix 32bit PAE pmd walk vs pmd_populate SMP race condition Greg KH
2012-06-07 4:14 ` [ 05/47] iwlwifi: update BT traffic load states correctly Greg KH
2012-06-07 4:14 ` [ 06/47] cifs: fix oops while traversing open file list (try #4) Greg KH
2012-06-07 4:14 ` [ 07/47] PARISC: fix boot failure on 32-bit systems caused by branch stubs placed before .text Greg KH
2012-06-07 4:14 ` [ 08/47] PARISC: fix TLB fault path on PA2.0 narrow systems Greg KH
2012-06-07 4:14 ` [ 09/47] solos-pci: Fix DMA support Greg KH
2012-06-07 4:14 ` [ 10/47] mac80211: fix ADDBA declined after suspend with wowlan Greg KH
2012-06-07 4:14 ` [ 11/47] NFSv4: Map NFS4ERR_SHARE_DENIED into an EACCES error instead of EIO Greg KH
2012-06-07 4:14 ` [ 12/47] drm/radeon: fix XFX quirk Greg KH
2012-06-07 4:14 ` [ 13/47] drm/i915: properly handle interlaced bit for sdvo dtd conversion Greg KH
2012-06-07 4:14 ` [ 14/47] drm/i915: wait for a vblank to pass after tv detect Greg KH
2012-06-07 4:14 ` [ 15/47] Bluetooth: Add support for Broadcom BCM20702A0 Greg KH
2012-06-07 4:14 ` [ 16/47] Bluetooth: Add support for BCM20702A0 [0a5c:21e3] Greg KH
2012-06-07 4:14 ` [ 17/47] Bluetooth: btusb: Add vendor specific ID (0a5c 21f3) for BCM20702A0 Greg KH
2012-06-07 4:14 ` [ 18/47] Bluetooth: btusb: add support for BCM20702A0 [0a5c:21e6] Greg KH
2012-06-07 4:14 ` [ 19/47] Bluetooth: btusb: Add USB device ID "0a5c 21e8" Greg KH
2012-06-07 4:14 ` [ 20/47] Bluetooth: btusb: Add vendor specific ID (0489 e042) for BCM20702A0 Greg KH
2012-06-07 4:14 ` [ 21/47] Bluetooth: btusb: typo in Broadcom SoftSailing id Greg KH
2012-06-07 4:14 ` [ 22/47] Add Foxconn / Hon Hai IDs for btusb module Greg KH
2012-06-07 4:14 ` [ 23/47] Bluetooth: Add support for Foxconn/Hon Hai AR5BBU22 0489:E03C Greg KH
2012-06-07 4:14 ` [ 24/47] ALSA: usb-audio: fix rate_list memory leak Greg KH
2012-06-07 4:14 ` [ 25/47] vfs: umount_tree() might be called on subtree that had never made it Greg KH
2012-06-07 4:14 ` [ 26/47] mtd: nand: fix scan_read_raw_oob Greg KH
2012-06-07 4:14 ` [ 27/47] drm/radeon: properly program gart on rv740, juniper, cypress, barts, hemlock Greg KH
2012-06-07 4:14 ` [ 28/47] drm/radeon: fix HD6790, HD6570 backend programming Greg KH
2012-06-07 4:14 ` [ 29/47] drm/ttm: Fix spinlock imbalance Greg KH
2012-06-07 4:14 ` [ 30/47] ipv4: Do not use dead fib_info entries Greg KH
2012-06-07 4:14 ` [ 31/47] ipv4: fix the rcu race between free_fib_info and ip_route_output_slow Greg KH
2012-06-07 4:14 ` [ 32/47] ipv6: fix incorrect ipsec fragment Greg KH
2012-06-07 4:14 ` [ 33/47] l2tp: fix oops in L2TP IP sockets for connect() AF_UNSPEC case Greg KH
2012-06-07 4:14 ` [ 34/47] pktgen: fix crash at module unload Greg KH
2012-06-07 4:14 ` [ 35/47] pktgen: fix module unload for good Greg KH
2012-06-07 4:14 ` [ 36/47] Revert "net: maintain namespace isolation between vlan and real device" Greg KH
2012-06-07 4:14 ` [ 37/47] sctp: check cached dst before using it Greg KH
2012-06-07 4:14 ` [ 38/47] skb: avoid unnecessary reallocations in __skb_cow Greg KH
2012-06-07 4:14 ` [ 39/47] xfrm: take net hdr len into account for esp payload size calculation Greg KH
2012-06-07 4:14 ` [ 40/47] ext4: force ro mount if ext4_setup_super() fails Greg KH
2012-06-07 4:14 ` [ 41/47] ext4: add missing save_error_info() to ext4_error() Greg KH
2012-06-07 4:14 ` [ 42/47] ext4: dont trash state flags in EXT4_IOC_SETFLAGS Greg KH
2012-06-07 4:14 ` [ 43/47] ext4: add ext4_mb_unload_buddy in the error path Greg KH
2012-06-07 4:14 ` [ 44/47] ext4: remove mb_groups before tearing down the buddy_cache Greg KH
2012-06-07 4:14 ` [ 45/47] drm/radeon/kms: add new BTC PCI ids Greg KH
2012-06-07 4:14 ` [ 46/47] ACPI battery: only refresh the sysfs files when pertinent information changes Greg KH
2012-06-07 4:14 ` [ 47/47] wl1251: fix oops on early interrupt Greg KH
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