search for: prealloc

Hi All I was reading through this: http://kashyapc.com/2011/12/02/little-more-disk-io-perf-improvement-with-fallocateing-a-qcow2-disk/ I was basically searching for pointers on improving disk I/O. I wanted to know the purpose of preallocation=full & preallocation=metadata , What is the difference between them ? and which one would yield a better disk I/O speed ? Appreciate your responses in this regard. Thanks Jatin

For raw, this allows "off" as a synonym for "sparse" (to make it consistent with qcow2). For qcow2, this allows "sparse" as a synonym for "off". It also adds qcow2 "full" preallocation, which is actually mapped to the qemu option "falloc" (see arguments about this on the qemu-devel mailing list, which we lost). This also updates the test. --- generator/actions.ml | 13 +++++++------ src/create.c | 16 ++++++++++++---- tests/create/...

On Tue, Jun 02, 2015 at 09:14:03AM +0530, Jatin Davey wrote: > Hi All > > I was reading through this: > > http://kashyapc.com/2011/12/02/little-more-disk-io-perf-improvement-with-fallocateing-a-qcow2-disk/ In my testing, the above method gives near-raw performance as it preallocated all the space ahead of time. The above test can now be done in a single command -- see option (3) below. > I was basically searching for pointers on improving disk I/O. > > I wanted to know the purpose of preallocation=full & preallocation=metadata > > > , What is the d...

Hi All, When I tried to create preallocated image with gluster , I am unable to create one The image gets created but not preallocated. [root@ ]# qemu-img create -f qcow2 -o preallocation=full gluster://host1.lab.eng.blr.redhat.com/rep3vol/vm3.img 3G Formatting 'gluster://dhcp37-61.lab.eng.blr.redhat.com/rep3vol/newvm3.img',...

...o the inalloca design <https://llvm.org/docs/InAlloca.html>, there should be a stackrestore after an invoke in both the non-exceptional and exceptional case (that doesn't seem to be happening in some cases as we've seen, but that's beside the point). Does it make sense to model a preallocated call as handling the cleanup of the stack in normal control flow (e.g. always for a normal call, and in the non-exceptional path for an invoke)? Then @llvm.call.preallocated.teardown is only necessary in the exceptional path to cleanup the stack. On Thu, Apr 16, 2020 at 1:40 PM Eli Friedman &l...

I believe that the changes to support --preallocate and --sparse together have broken --preallocate by itself (commit f3873b3d88b61167b106e7b9227a20147f8f6197) The previous behavior of --preallocate was to do just that: reserve blocks in the filesystem WITHOUT setting the size of the file to the final length. The reported filesize would change...

When creating qcow2 images using virt-builder, is there a way to specify the qcow2 preallocation, as possible with qemu-img create -o preallocation=metada , for example? TIA, Y.

...wrote: > > > On Tue, May 17, 2016 at 03:41:53PM +0100, Richard W.M. Jones wrote: > > > On Tue, May 17, 2016 at 05:15:57PM +0300, Yaniv Kaul wrote: > > > > When creating qcow2 images using virt-builder, is there a way to > > specify > > > > the qcow2 preallocation, as possible with qemu-img create -o > > > > preallocation=metada , for example? > > > > > > No .. but .. it does default to preallocation=metadata provided that > > > the output format is qcow2: > > > > > > > > https://github.com/...

I've read in Phil Spector's new book that it's a good idea to preallocate a big matrix, like u <- matrix(0,nrow,ncol) # (1) Now, I read contents of a huge matrix from a Fortran binary dump. u <- readBin(con,what="double",n=nrow*ncol) # (2) If I do (1) and then (2), u is a vector, obviously it's either reallocated or its matrix nature is lost...

On Tue, May 17, 2016 at 03:41:53PM +0100, Richard W.M. Jones wrote: > On Tue, May 17, 2016 at 05:15:57PM +0300, Yaniv Kaul wrote: > > When creating qcow2 images using virt-builder, is there a way to specify > > the qcow2 preallocation, as possible with qemu-img create -o > > preallocation=metada , for example? > > No .. but .. it does default to preallocation=metadata provided that > the output format is qcow2: > > https://github.com/libguestfs/libguestfs/blob/master/builder/builder.ml#L582-L585 I sh...

...at 2:20 PM Eli Friedman <efriedma at quicinc.com> wrote: > This would specifically be for cases where we try to rewrite the > signature? I would assume we should forbid rewriting the signature of a > call with an operand bundle. And once some optimization drops the bundle > and preallocated marking, to allow such rewriting, the signature doesn’t > need to match anymore. > Yes, I really would like to enable DAE and other signature rewriting IPO transforms. Maybe today DAE doesn't run on calls with bundles, but this feature is designed to allow the non-preallocated argume...

Hi folks I am trying to install CentOS 5.2 in Vmware Server environment. In my VM disk space is not preallocated for the virtual disk (dynamically). The installer doesn't find the disk. When preallocating 6 GB there is no problem. See screenshot[0] Any ideas? kind regards Sven [0] http://bayimg.com/image/lamidaabe.jpg

https://bugzilla.samba.org/show_bug.cgi?id=8775 Summary: Preallocate option doesn't work with recursive? Product: rsync Version: 3.1.0 Platform: x64 OS/Version: Linux Status: NEW Severity: normal Priority: P5 Component: core AssignedTo: wayned at samba.org Reporte...

...s occur all throughout the file, not just at the end of the file. File names look like this: Db_20080402_0003_DB.BAK Db_20080403_0003_DB.BAK Therefore, I can use the .fuzzy switch as a basis for rsync. I want to take this one step farther. What I would like to accomplish is the merging of the .preallocate patch and the .fuzzy option. When these 2 switches are used together (at least on Windows platforms), I want rsync to determine which fuzzy file to use (from the fuzzy_distance() function), but then go ahead and preallocate the new file, not with posix_fallocate(), but with the contents of the...

When I use the preallocate patch and create a 77GB file using the function I get a CPU spike on the server-side. The spike lasts about 20 minutes and uses about 20%-25% of the cpu associated with the rsync instance creating the file. The spike is directly linked to the time it takes to create the file. I compiled rsync...

...gt; On Tue, May 17, 2016 at 03:41:53PM +0100, Richard W.M. Jones wrote: > > > > On Tue, May 17, 2016 at 05:15:57PM +0300, Yaniv Kaul wrote: > > > > > When creating qcow2 images using virt-builder, is there a way to > > > specify > > > > > the qcow2 preallocation, as possible with qemu-img create -o > > > > > preallocation=metada , for example? > > > > > > > > No .. but .. it does default to preallocation=metadata provided that > > > > the output format is qcow2: > > > > > > > >...

...andom thoughts in no particular order. It would be nice to use `-oa sparse' etc for compatibility with virt-v2v, but that possibly closes off future options for replacing the horrible OCaml Arg module with GNU getopt_long (-oa == -o + -a). I initially tried to implement `--output-alloc sparse|preallocated' using the Planner. I added an extra planner flag [`Alloc, ("sparse"|"preallocated")]. I added extra transitions such as `Copy_sparse_never ("cp --sparse=never"). The problem is that some output locations don't support sparse output, eg. writing to a blo...

Hi Timo, Any chance the mbox/mdbox writer code could be modified to do physical preallocation on files to help avoid file(system) fragmentation? Constantly appending a file is the prime recipe for causing fragmentation, and mbox is notorious for this--not a fault of Dovecot but the nature of the mbox beast. Obviously maildir doesn't have such a problem, but some (many?) of us stil...

...nowing about it, there is no reason to add a new way to do the same thing. Thanks, Reid The last RFC: http://lists.llvm.org/pipermail/llvm-dev/2013-July/064218.html Current inalloca docs: https://llvm.org/docs/InAlloca.html ---------------- # RFC: Replace inalloca with llvm.call.setup and preallocated In order to pass non-trivially copyable objects by value in a way that is compatible with the Visual C++ compiler on 32-bit x86, Clang has to be able to separate the allocation of call argument memory from the call site. The `inalloca` feature was added to LLVM for this purpose. However, this...

...ship and - * permissions correctly if required. + (* As a special case, allow output to a block device or + * symlink to a block device. In this case we don't + * create/overwrite the block device. (RHBZ#1868690). *) - (* What output preallocation mode should we use? *) - let preallocation = - match t.target_format, cmdline.output_alloc with - | ("raw"|"qcow2"), Sparse -> Some "sparse" - | ("raw"|"qcow2"), Preallocated -> Some "full&qu...