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, Ian Campbell <ian.campbell@citrix.com>,
David Vrabel <david.vrabel@citrix.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Subject: [ 06/47] xen: correctly check for pending events when restoring irq flags
Date: Fri, 04 May 2012 13:42:50 -0700 [thread overview]
Message-ID: <20120504204245.376338050@linuxfoundation.org> (raw)
In-Reply-To: <20120504204307.GA13761@kroah.com>
3.0-stable review patch. If anyone has any objections, please let me know.
------------------
From: David Vrabel <david.vrabel@citrix.com>
commit 7eb7ce4d2e8991aff4ecb71a81949a907ca755ac upstream.
In xen_restore_fl_direct(), xen_force_evtchn_callback() was being
called even if no events were pending. This resulted in (depending on
workload) about a 100 times as many xen_version hypercalls as
necessary.
Fix this by correcting the sense of the conditional jump.
This seems to give a significant performance benefit for some
workloads.
There is some subtle tricksy "..since the check here is trying to
check both pending and masked in a single cmpw, but I think this is
correct. It will call check_events now only when the combined
mask+pending word is 0x0001 (aka unmasked, pending)." (Ian)
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/xen/xen-asm.S | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/xen/xen-asm.S
+++ b/arch/x86/xen/xen-asm.S
@@ -96,7 +96,7 @@ ENTRY(xen_restore_fl_direct)
/* check for unmasked and pending */
cmpw $0x0001, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_pending
- jz 1f
+ jnz 1f
2: call check_events
1:
ENDPATCH(xen_restore_fl_direct)
next prev parent reply other threads:[~2012-05-04 21:02 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-04 20:43 [ 00/47] 3.0.31-stable review Greg KH
2012-05-04 20:42 ` [ 01/47] nfs: Enclose hostname in brackets when needed in nfs_do_root_mount Greg KH
2012-05-04 20:42 ` [ 02/47] NFSv4: Ensure that the LOCK code sets exception->inode Greg KH
2012-05-04 20:42 ` [ 03/47] NFSv4: Ensure that we check lock exclusive/shared type against open modes Greg KH
2012-05-04 20:42 ` [ 04/47] x86, apic: APIC code touches invalid MSR on P5 class machines Greg KH
2012-05-04 20:42 ` [ 05/47] Revert "autofs: work around unhappy compat problem on x86-64" Greg KH
2012-05-04 20:42 ` Greg KH [this message]
2012-05-04 20:42 ` [ 07/47] xen/smp: Fix crash when booting with ACPI hotplug CPUs Greg KH
2012-05-04 20:42 ` [ 08/47] ASoC: dapm: Ensure power gets managed for line widgets Greg KH
2012-05-04 20:42 ` [ 09/47] dmaengine: at_hdmac: remove clear-on-read in atc_dostart() Greg KH
2012-05-04 20:42 ` [ 10/47] hwmon: fam15h_power: fix bogus values with current BIOSes Greg KH
2012-05-04 20:42 ` [ 11/47] hwmon: (fam15h_power) Fix pci_device_id array Greg KH
2012-05-04 20:42 ` [ 12/47] drm/i915: handle input/output sdvo timings separately in mode_set Greg KH
2012-05-04 20:42 ` [ 13/47] drm/i915: fix integer overflow in i915_gem_execbuffer2() Greg KH
2012-05-04 20:42 ` [ 14/47] drm/i915: fix integer overflow in i915_gem_do_execbuffer() Greg KH
2012-05-04 20:42 ` [ 15/47] nl80211: ensure interface is up in various APIs Greg KH
2012-05-04 20:43 ` [ 16/47] EHCI: fix criterion for resuming the root hub Greg KH
2012-05-04 20:43 ` [ 17/47] brcm80211: smac: resume transmit fifo upon receiving frames Greg KH
2012-05-04 20:43 ` [ 18/47] Fix modpost failures in fedora 17 Greg KH
2012-05-04 20:43 ` [ 19/47] KVM: unmap pages from the iommu when slots are removed Greg KH
2012-05-04 20:43 ` [ 20/47] mmc: unbreak sdhci-esdhc-imx on i.MX25 Greg KH
2012-05-04 20:43 ` [ 21/47] nfsd: fix b0rken error value for setattr on read-only mount Greg KH
2012-05-04 20:43 ` [ 22/47] nfsd: fix error values returned by nfsd4_lockt() when nfsd_open() fails Greg KH
2012-05-04 20:43 ` [ 23/47] [PATCH] Revert "usb: Fix build error due to dma_mask is not at pdev_archdata at ARM" Greg KH
2012-05-07 1:59 ` Ben Hutchings
2012-05-08 0:31 ` Greg KH
2012-05-04 20:43 ` [ 24/47] USB: cdc-wdm: fix race leading leading to memory corruption Greg KH
2012-05-04 20:43 ` [ 25/47] USB: EHCI: fix crash during suspend on ASUS computers Greg KH
2012-05-04 20:43 ` [ 26/47] USB: gadget: storage gadgets send wrong error code for unknown commands Greg KH
2012-05-04 20:43 ` [ 27/47] usb gadget: uvc: uvc_request_data::length field must be signed Greg KH
2012-05-04 20:43 ` [ 28/47] pipes: add a "packetized pipe" mode for writing Greg KH
2012-05-04 20:43 ` [ 29/47] autofs: make the autofsv5 packet file descriptor use a packetized pipe Greg KH
2012-05-04 20:43 ` [ 30/47] ARM: 7403/1: tls: remove covert channel via TPIDRURW Greg KH
2012-05-04 20:43 ` [ 31/47] SCSI: libsas: fix sas_find_bcast_phy() in the presence of vacant phys Greg KH
2012-05-04 20:43 ` [ 32/47] SCSI: libsas: fix false positive device attached conditions Greg KH
2012-05-04 20:43 ` [ 33/47] efi: Add new variable attributes Greg KH
2012-05-04 20:43 ` [ 34/47] efivars: String functions Greg KH
2012-05-04 20:43 ` [ 35/47] efivars: fix warnings when CONFIG_PSTORE=n Greg KH
2012-05-04 20:43 ` [ 36/47] efi: Validate UEFI boot variables Greg KH
2012-05-04 20:43 ` [ 37/47] efivars: Improve variable validation Greg KH
2012-05-04 20:43 ` [ 38/47] hwmon: (coretemp) Increase CPU core limit Greg KH
2012-05-04 20:43 ` [ 39/47] hwmon: (coretemp) fix oops on cpu unplug Greg KH
2012-05-04 20:43 ` [ 40/47] libata: skip old error history when counting probe trials Greg KH
2012-05-04 20:43 ` [ 41/47] i2c: pnx: Disable clk in suspend Greg KH
2012-05-04 20:43 ` [ 42/47] ipw2200: Fix race condition in the command completion acknowledge Greg KH
2012-05-04 20:43 ` [ 43/47] mac80211: fix AP mode EAP tx for VLAN stations Greg KH
2012-05-04 20:43 ` [ 44/47] rtlwifi: Fix oops on unload Greg KH
2012-05-04 20:43 ` [ 45/47] wl1251: fix crash on remove due to premature kfree Greg KH
2012-05-04 20:43 ` [ 46/47] wl1251: fix crash on remove due to leftover work item Greg KH
2012-05-04 20:43 ` [ 47/47] sched: Fix nohz load accounting -- again! Greg KH
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20120504204245.376338050@linuxfoundation.org \
--to=gregkh@linuxfoundation.org \
--cc=akpm@linux-foundation.org \
--cc=alan@lxorguk.ukuu.org.uk \
--cc=david.vrabel@citrix.com \
--cc=ian.campbell@citrix.com \
--cc=konrad.wilk@oracle.com \
--cc=linux-kernel@vger.kernel.org \
--cc=stable@vger.kernel.org \
--cc=torvalds@linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox