Re: [Qemu-block] [PATCH] nvme: Implement Write Zeroes

2017-05-05 Thread Christoph Hellwig
On Fri, May 05, 2017 at 12:03:40PM +0200, Paolo Bonzini wrote: > While that's allowed and it makes sense indeed on SSDs, for QEMU's > typical usage it can lead to fragmentation and worse performance. On > extent-based file systems, write zeroes without deallocate can be > implemented very

Re: [Qemu-block] [PATCH] nvme: Implement Write Zeroes

2017-05-05 Thread Paolo Bonzini
On 05/05/2017 11:51, Christoph Hellwig wrote: >> could you pass BDRV_REQ_MAY_UNMAP for the flags here if the deallocate >> bit (dword 12 bit 25) is set? > In fact we should do that unconditonally. The deallocate bit is new > in 1.3 (which we don't claim to support) and forces deallocating, but

Re: [Qemu-block] [PATCH] nvme: Implement Write Zeroes

2017-05-05 Thread Christoph Hellwig
On Fri, May 05, 2017 at 11:30:11AM +0200, Paolo Bonzini wrote: > could you pass BDRV_REQ_MAY_UNMAP for the flags here if the deallocate > bit (dword 12 bit 25) is set? In fact we should do that unconditonally. The deallocate bit is new in 1.3 (which we don't claim to support) and forces

Re: [Qemu-block] [PATCH] nvme: Implement Write Zeroes

2017-05-05 Thread Paolo Bonzini
On 05/05/2017 11:00, Christoph Hellwig wrote: > Signed-off-by: Keith Busch > [hch: ported over from qemu-nvme.git to mainline] > Signed-off-by: Christoph Hellwig > --- > hw/block/nvme.c | 26 ++ > hw/block/nvme.h | 1 + > 2 files

[Qemu-block] [PATCH] nvme: Implement Write Zeroes

2017-05-05 Thread Christoph Hellwig
Signed-off-by: Keith Busch [hch: ported over from qemu-nvme.git to mainline] Signed-off-by: Christoph Hellwig --- hw/block/nvme.c | 26 ++ hw/block/nvme.h | 1 + 2 files changed, 27 insertions(+) diff --git a/hw/block/nvme.c