[Qemu-devel] iSCSI support for QEMU

2011-06-11 Thread ronnie sahlberg
Sorry about the missing subject line in the previous mail Got confused when using git-send-patch :-) regards ronnie sahlberg On Sun, Jun 12, 2011 at 12:47 PM, Ronnie Sahlberg ronniesahlb...@gmail.com wrote: Please find attached a patch to add built-in support for iSCSI into QEMU. Please review

[Qemu-devel] iSCSI support for QEMU, update

2011-05-07 Thread Ronnie Sahlberg
This is a patch that adds support for iSCSI to QEMU when QEMU is built against libiscsi (https://github.com/sahlberg/libiscsi) ISCSI devices are specified using a special iSCSI URL: -drive file=iscsi://10.1.1.1:3260/iqn.ronnie.test/1 This allows a guest to access iscsi devices without

Re: [Qemu-devel] iSCSI support for QEMU, update

2011-04-22 Thread ronnie sahlberg
Thanks, On Fri, Apr 22, 2011 at 2:08 PM, Christoph Hellwig h...@lst.de wrote: On Fri, Apr 22, 2011 at 06:23:58AM +1000, ronniesahlb...@gmail.com wrote: iSCSI block driver for QEMU Please find an updated iSCSI patch. This patch adds setting FUA on all writes when the bit BDRV_O_CACHE_WB is

Re: [Qemu-devel] iSCSI support for QEMU, update

2011-04-22 Thread Christoph Hellwig
On Fri, Apr 22, 2011 at 04:08:57PM +1000, ronnie sahlberg wrote: So I should set FUA when BDRV_O_CACHE_WB==0 or BDRV_O_NOCACHE==1 right? At this point you need to set it if either the BDRV_O_CACHE_WB and BDRV_O_NOCACHE flags are set. And yes, the naming of the nocache flag is rather

Re: [Qemu-devel] iSCSI support for QEMU, update

2011-04-22 Thread ronnie sahlberg
Ok, I am confused On Fri, Apr 22, 2011 at 4:13 PM, Christoph Hellwig h...@lst.de wrote: On Fri, Apr 22, 2011 at 04:08:57PM +1000, ronnie sahlberg wrote: So I should set FUA when BDRV_O_CACHE_WB==0  or  BDRV_O_NOCACHE==1 right? At this point you need to set it if either the BDRV_O_CACHE_WB

Re: [Qemu-devel] iSCSI support for QEMU, update

2011-04-22 Thread Christoph Hellwig
On Fri, Apr 22, 2011 at 04:35:11PM +1000, ronnie sahlberg wrote: Ok, I am confused And this time it's my fault, sorry. I have to set FUA if the WB(I guessed this meant write-back) flag is set? Not the opposite (I assume opposite of write-back is write-through) ? Sorry, I meant exactly the

[Qemu-devel] iSCSI support for QEMU

2011-04-21 Thread Ronnie Sahlberg
Please find attached a new version of the patch for iSCSI support. iSCSI support is automaticallt detected and activated during configure/build if the libiscsi library is available on the build host. This library is available at : https://github.com/sahlberg/libiscsi This new version contains

Re: [Qemu-devel] iSCSI support for QEMU

2011-04-21 Thread Christoph Hellwig
On Thu, Apr 21, 2011 at 06:43:10PM +1000, Ronnie Sahlberg wrote: Some basic tests thatve been performed show it to be significantly faster than an out-of-the-box open-iscsi mounted LUN being accessed by default QEMU i/o options. Which isn't a useful comparism. qemu's default is the braindead

Re: [Qemu-devel] iSCSI support for QEMU

2011-04-21 Thread ronnie sahlberg
Please re-read my post or read the patch. It has O_DIRECT like behaviour in that it will not pollute the hosts cache. This for the simple reason that the host is not aware that there is any block i/o happening. In my patch, there are NO data integrity issues. Data is sent out on the wire

Re: [Qemu-devel] iSCSI support for QEMU

2011-04-21 Thread Christoph Hellwig
In my patch, there are NO data integrity issues. Data is sent out on the wire immediately as the guest issues the write. Once the guest issues a flush call, the flush call will not terminate until the SYNCCACHE10 task has completed. No guest will even issue a cache flush, as we claim to be

Re: [Qemu-devel] iSCSI support for QEMU

2011-04-21 Thread ronnie sahlberg
On Thu, Apr 21, 2011 at 7:09 PM, Christoph Hellwig h...@lst.de wrote: In my patch, there are NO data integrity issues. Data is sent out on the wire immediately as the guest issues the write. Once the guest issues a flush call, the flush call will not terminate until the SYNCCACHE10 task has

Re: [Qemu-devel] iSCSI support for QEMU

2011-04-21 Thread ronnie sahlberg
Christoph, I think you misread my test. My test is pure reading : sudo time dd if=/dev/sda of=/dev/null bs=1M There are no writes involved at all in this test, only a huge number of READ10 being sent to the target, or in the case of when using QEMU+openiscsi-mounted-lun sometimes being served

Re: [Qemu-devel] iSCSI support for QEMU

2011-04-21 Thread Stefan Hajnoczi
On Thu, Apr 21, 2011 at 10:28 AM, ronnie sahlberg ronniesahlb...@gmail.com wrote: On Thu, Apr 21, 2011 at 7:09 PM, Christoph Hellwig h...@lst.de wrote: We only claim WCE=1 to the guest if cache=writeback or cache=none are set.  So ignoring the issue of having a cache on the initiator side you

Re: [Qemu-devel] iSCSI support for QEMU

2011-04-21 Thread ronnie sahlberg
On Thu, Apr 21, 2011 at 8:58 PM, Stefan Hajnoczi stefa...@gmail.com wrote: On Thu, Apr 21, 2011 at 10:28 AM, ronnie sahlberg ronniesahlb...@gmail.com wrote: On Thu, Apr 21, 2011 at 7:09 PM, Christoph Hellwig h...@lst.de wrote: We only claim WCE=1 to the guest if cache=writeback or cache=none

Re: [Qemu-devel] iSCSI support for QEMU

2011-04-21 Thread Stefan Hajnoczi
On Thu, Apr 21, 2011 at 12:12 PM, ronnie sahlberg ronniesahlb...@gmail.com wrote: On Thu, Apr 21, 2011 at 8:58 PM, Stefan Hajnoczi stefa...@gmail.com wrote: On Thu, Apr 21, 2011 at 10:28 AM, ronnie sahlberg ronniesahlb...@gmail.com wrote: On Thu, Apr 21, 2011 at 7:09 PM, Christoph Hellwig

Re: [Qemu-devel] iSCSI support for QEMU

2011-04-21 Thread ronnie sahlberg
Stephan, I understand. Let me re-send a patch tomorrow that can optionally enable/force FUA bits for write. There are some high-volume arrays that advertise support but fail any cdb with FUA, FUA_NV bits set with sense, so it needs to be made optional. regards ronnie sahlberg On Thu, Apr 21,

Re: [Qemu-devel] iSCSI support for QEMU

2011-04-21 Thread Kevin Wolf
Am 21.04.2011 13:36, schrieb ronnie sahlberg: Stephan, I understand. Let me re-send a patch tomorrow that can optionally enable/force FUA bits for write. There are some high-volume arrays that advertise support but fail any cdb with FUA, FUA_NV bits set with sense, so it needs to be made

Re: [Qemu-devel] iSCSI support for QEMU

2011-04-21 Thread Stefan Hajnoczi
On Thu, Apr 21, 2011 at 12:36 PM, ronnie sahlberg ronniesahlb...@gmail.com wrote: I understand. Let me re-send a patch tomorrow that can optionally enable/force FUA bits for write. There are some high-volume arrays that advertise support but fail any cdb with FUA, FUA_NV bits set with sense,

Re: [Qemu-devel] iSCSI support for QEMU

2011-04-21 Thread Christoph Hellwig
On Thu, Apr 21, 2011 at 09:36:12PM +1000, ronnie sahlberg wrote: There are some high-volume arrays that advertise support but fail any cdb with FUA, FUA_NV bits set with sense, so it needs to be made optional. Which on would that be? Linux uses the FUA bit if the device advertises support via

[Qemu-devel] iSCSI support for QEMU, update

2011-04-21 Thread ronniesahlberg
iSCSI block driver for QEMU Please find an updated iSCSI patch. This patch adds setting FUA on all writes when the bit BDRV_O_CACHE_WB is not set. regards ronnie sahlberg From: Ronnie Sahlberg ronniesahlb...@gmail.com Subject: iSCSI support for QEMU, update In-Reply-To:

Re: [Qemu-devel] iSCSI support for QEMU

2011-04-21 Thread ronnie sahlberg
On Thu, Apr 21, 2011 at 10:49 PM, Christoph Hellwig h...@lst.de wrote: On Thu, Apr 21, 2011 at 09:36:12PM +1000, ronnie sahlberg wrote: There are some high-volume arrays that advertise support but fail any cdb with FUA, FUA_NV bits set with sense, so it needs to be made optional. Which on

Re: [Qemu-devel] iSCSI support for QEMU, update

2011-04-21 Thread Christoph Hellwig
On Fri, Apr 22, 2011 at 06:23:58AM +1000, ronniesahlb...@gmail.com wrote: iSCSI block driver for QEMU Please find an updated iSCSI patch. This patch adds setting FUA on all writes when the bit BDRV_O_CACHE_WB is not set. At this point you need to check for BDRV_O_CACHE_WB and BDRV_O_NOCACHE