Displaying 9 results from an estimated 9 matches for "fadvic".
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fadvice
2020 Aug 07
2
Re: [PATCH nbdkit] file: Implement cache=none and fadvise=normal|random|sequential.
...s <rjones@redhat.com> wrote:
> > These ones?
> > https://www.redhat.com/archives/libguestfs/2020-August/msg00078.html
>
> No, we had a bug when copying image from glance caused sanlock timeouts
> because of the unpredictable page cache flushes.
>
> We tried to use fadvice but it did not help. The only way to avoid such issues
> is with O_SYNC or O_DIRECT. O_SYNC is much slower but this is the path
> we took for now in this flow.
I'm interested in more background about this, because while it is true
that O_DIRECT and POSIX_FADV_DONTNEED are not exactly eq...
2020 Aug 07
2
Re: [PATCH nbdkit] file: Implement cache=none and fadvise=normal|random|sequential.
On Fri, Aug 07, 2020 at 04:43:12PM +0300, Nir Soffer wrote:
> On Fri, Aug 7, 2020, 16:16 Richard W.M. Jones <rjones@redhat.com> wrote:
> > I'm not sure if or even how we could ever do a robust O_DIRECT
> >
>
> We can let the plugin an filter deal with that. The simplest solution is to
> drop it on the user and require aligned requests.
I mean this is very error
2020 Aug 10
1
Re: [PATCH nbdkit] file: Implement cache=none and fadvise=normal|random|sequential.
...gt; > > > https://www.redhat.com/archives/libguestfs/2020-August/msg00078.html
> > >
> > > No, we had a bug when copying image from glance caused sanlock timeouts
> > > because of the unpredictable page cache flushes.
> > >
> > > We tried to use fadvice but it did not help. The only way to avoid such issues
> > > is with O_SYNC or O_DIRECT. O_SYNC is much slower but this is the path
> > > we took for now in this flow.
> >
> > I'm interested in more background about this, because while it is true
> > that O_...
2020 Aug 07
0
Re: [PATCH nbdkit] file: Implement cache=none and fadvise=normal|random|sequential.
...:
> > > These ones?
> > > https://www.redhat.com/archives/libguestfs/2020-August/msg00078.html
> >
> > No, we had a bug when copying image from glance caused sanlock timeouts
> > because of the unpredictable page cache flushes.
> >
> > We tried to use fadvice but it did not help. The only way to avoid such issues
> > is with O_SYNC or O_DIRECT. O_SYNC is much slower but this is the path
> > we took for now in this flow.
>
> I'm interested in more background about this, because while it is true
> that O_DIRECT and POSIX_FADV_DON...
2020 Aug 08
1
Re: [PATCH nbdkit] plugins: file: More standard cache mode names
...ache and evicting the pages does not make much sense, since
when reading the pages are not in the cache. So why do you use the cache?
I think we are mixing different things in the current code. Flushing after every
write is almost never needed, but if needed it should be possible to use it
without fadvice=DONTNEED to keep a useful cache when reading.
I think the DONTNEED flag should be separate from cache=writesthrough. In dd
this can be done using iflag=nocache or oflag=nocache, and syncing after every
write can be done using oflag=dsync/sync. If you want both you can use
oflag=nocache,dsync.
&g...
2020 Aug 07
0
Re: [PATCH nbdkit] file: Implement cache=none and fadvise=normal|random|sequential.
...gt; We already tried this with dd and the results were not good.
>
> These ones?
> https://www.redhat.com/archives/libguestfs/2020-August/msg00078.html
No, we had a bug when copying image from glance caused sanlock timeouts
because of the unpredictable page cache flushes.
We tried to use fadvice but it did not help. The only way to avoid such issues
is with O_SYNC or O_DIRECT. O_SYNC is much slower but this is the path
we took for now in this flow.
>
> Rich.
>
> --
> Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
> Read my programming and...
2013 Jan 13
6
[Bug 9560] New: drop-cache option
https://bugzilla.samba.org/show_bug.cgi?id=9560
Summary: drop-cache option
Product: rsync
Version: 3.0.9
Platform: All
OS/Version: All
Status: NEW
Severity: normal
Priority: P5
Component: core
AssignedTo: wayned at samba.org
ReportedBy: colundrum at gmail.com
QAContact: rsync-qa at
2010 Nov 04
4
fadvise DONTNEED implementation (or lack thereof)
I've recently been trying to track down the root cause of my server's
persistent issue of thrashing horribly after being left inactive. It
seems that the issue is likely my nightly backup schedule (using rsync)
which traverses my entire 50GB home directory. I was surprised to find
that rsync does not use fadvise to notify the kernel of its use-once
data usage pattern.
It looks like a
2020 Aug 07
2
[PATCH nbdkit] plugins: file: More standard cache mode names
The new cache=none mode is misleading since it does not avoid usage of
the page cache. When using shared storage, we may get stale data from
the page cache. When writing, we flush after every write which is
inefficient and unneeded.
Rename the cache modes to:
- writeback - write complete when the system call returned, and the data
was copied to the page cache.
- writethrough - write completes