Re: [PATCH 4/6] qemu-img: rebase: avoid unnecessary COW operations

2023-08-29 Thread Andrey Drobyshev
On 8/25/23 18:00, Hanna Czenczek wrote: > On 01.06.23 21:28, Andrey Drobyshev via wrote: >> When rebasing an image from one backing file to another, we need to >> compare data from old and new backings.  If the diff between that data >> happens to be unaligned to the target cluster size, we might

Re: [PATCH 4/6] qemu-img: rebase: avoid unnecessary COW operations

2023-08-25 Thread Hanna Czenczek
On 01.06.23 21:28, Andrey Drobyshev via wrote: When rebasing an image from one backing file to another, we need to compare data from old and new backings. If the diff between that data happens to be unaligned to the target cluster size, we might end up doing partial writes, which would lead to

Re: [PATCH 4/6] qemu-img: rebase: avoid unnecessary COW operations

2023-06-21 Thread Denis V. Lunev
On 6/1/23 21:28, Andrey Drobyshev wrote: When rebasing an image from one backing file to another, we need to compare data from old and new backings. If the diff between that data happens to be unaligned to the target cluster size, we might end up doing partial writes, which would lead to

[PATCH 4/6] qemu-img: rebase: avoid unnecessary COW operations

2023-06-01 Thread Andrey Drobyshev via
When rebasing an image from one backing file to another, we need to compare data from old and new backings. If the diff between that data happens to be unaligned to the target cluster size, we might end up doing partial writes, which would lead to copy-on-write and additional IO. Consider the