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Re: [Qemu-devel] [Qemu-block] [PATCH] block, migration: Use qemu_madvise
From: |
Pankaj Gupta |
Subject: |
Re: [Qemu-devel] [Qemu-block] [PATCH] block, migration: Use qemu_madvise inplace of madvise |
Date: |
Fri, 17 Feb 2017 06:30:28 -0500 (EST) |
Thanks for your comments. I have below query.
>
> On Fri 17 Feb 2017 09:06:04 AM CET, Pankaj Gupta wrote:
> > To maintain consistency at all the places use qemu_madvise wrapper
> > inplace of madvise call.
>
> > if (length > 0) {
> > - madvise((uint8_t *) t + offset, length, MADV_DONTNEED);
> > + qemu_madvise((uint8_t *) t + offset, length, QEMU_MADV_DONTNEED);
>
> This was changed two months ago from qemu_madvise() to madvise(), is
> there any reason why you want to revert that change? Those two calls are
> not equivalent, please see commit 2f2c8d6b371cfc6689affb0b7e for an
> explanation.
>
> > - if (madvise(start, length, MADV_DONTNEED)) {
> > + if (qemu_madvise(start, length, QEMU_MADV_DONTNEED)) {
> > error_report("%s MADV_DONTNEED: %s", __func__, strerror(errno));
I checked history of only change related to 'postcopy'.
For my linux machine:
./config-host.mak
CONFIG_MADVISE=y
CONFIG_POSIX_MADVISE=y
As both these options are set for Linux, every time we call call 'qemu_madvise'
==>"madvise(addr, len, advice);" will
be compiled/called. I don't understand why '2f2c8d6b371cfc6689affb0b7e'
explicitly changed for :"#ifdef CONFIG_LINUX"
I think its better to write generic function maybe in a wrapper then to
conditionally set something at different places.
int qemu_madvise(void *addr, size_t len, int advice)
{
if (advice == QEMU_MADV_INVALID) {
errno = EINVAL;
return -1;
}
#if defined(CONFIG_MADVISE)
return madvise(addr, len, advice);
#elif defined(CONFIG_POSIX_MADVISE)
return posix_madvise(addr, len, advice);
#else
errno = EINVAL;
return -1;
#endif
}
>
> And this is the same case.
>
> Berto
>
- [Qemu-devel] [PATCH] block, migration: Use qemu_madvise inplace of madvise, Pankaj Gupta, 2017/02/17
- Re: [Qemu-devel] [PATCH] block, migration: Use qemu_madvise inplace of madvise, Kevin Wolf, 2017/02/17
- Re: [Qemu-devel] [Qemu-block] [PATCH] block, migration: Use qemu_madvise inplace of madvise, Alberto Garcia, 2017/02/17
- Re: [Qemu-devel] [Qemu-block] [PATCH] block, migration: Use qemu_madvise inplace of madvise,
Pankaj Gupta <=
- Re: [Qemu-devel] [Qemu-block] [PATCH] block, migration: Use qemu_madvise inplace of madvise, Alberto Garcia, 2017/02/17