similar to: [PATCH nbdkit] file: Implement cache=none and fadvise=normal|random|sequential.

On Fri, Aug 07, 2020 at 07:53:13AM -0500, Eric Blake wrote: > >$ free -m; time ./nbdkit file /var/tmp/random fadvise=sequential cache=none --run 'qemu-img convert -n -p -m 16 -W $nbd "json:{\"file.driver\":\"null-co\",\"file.size\":\"1E\"}"' ; free -m ; cachestats /var/tmp/random > > Hmm - the -W actually says that qemu-img is

On 8/7/20 6:31 AM, Richard W.M. Jones wrote: > You can use these flags as described in the manual page to optimize > access patterns, and to get better behaviour with the page cache in > some scenarios. And if you guess wrong, it is only a performance penalty, not a correctness issue. > > For my testing I used the cachedel and cachestats utilities written by > Julius Plenz

On Fri, Aug 7, 2020, 16:16 Richard W.M. Jones <rjones@redhat.com> wrote: > On Fri, Aug 07, 2020 at 07:53:13AM -0500, Eric Blake wrote: > > >$ free -m; time ./nbdkit file /var/tmp/random fadvise=sequential > cache=none --run 'qemu-img convert -n -p -m 16 -W $nbd >

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

On Sat, Aug 08, 2020 at 01:24:02AM +0300, Nir Soffer wrote: > 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. > Hmm. This isn't actually what the cache=none parameter is currently doing.

On Sun, Aug 9, 2020 at 12:28 AM Richard W.M. Jones <rjones@redhat.com> wrote: > > On Sat, Aug 08, 2020 at 01:24:02AM +0300, Nir Soffer wrote: > > 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 > >

While going through an old todo list I found that these patches had fallen by the way-side. About a year ago I initiated a discussion[1] with the Linux kernel folks regarding the lack of any useable fadvise support on the kernel side. As a result, I was observing extremely poor performance on my server after backup as executable pages were being swapped out in favor of data waiting to be flushed

Hi all, In a conversation between me, Milind and Csaba, Milind pointed out fadvise(2) [1] and its potential benefits to Glusterfs' caching translators like read-ahead etc. After discussing about it, we agreed that our performance translators can leverage the hints to provide better performance. Now the question is how commonly applications actually provide hints? Is it something that is used

https://bugzilla.samba.org/show_bug.cgi?id=7004 Summary: Use posix_fadvise to free cached file contents when done Product: rsync Version: 3.0.6 Platform: All OS/Version: Linux Status: NEW Severity: enhancement Priority: P3 Component: core AssignedTo: wayned at samba.org ReportedBy: ted at

On Fri, Aug 11, 2017 at 05:50:47PM +0530, Ravishankar N wrote: > > > On 08/11/2017 04:51 PM, Niels de Vos wrote: > > On Fri, Aug 11, 2017 at 12:47:47AM -0400, Raghavendra Gowdappa wrote: > > > Hi all, > > > > > > In a conversation between me, Milind and Csaba, Milind pointed out > > > fadvise(2) [1] and its potential benefits to Glusterfs'

Add wrappers around posix_fadvise and use them in places we were calling posix_fadvise directly before. Also in virt-builder we were doing this (and ignoring the result): posix_fadvise (fd, 0, 0, POSIX_FADV_RANDOM|POSIX_FADV_DONTNEED); However the POSIX_FADV_* flags are _not_ bitmasks! In fact POSIX_FADV_RANDOM|POSIX_FADV_DONTNEED == POSIX_FADV_NOREUSE so we were giving a completely

Warning for kernel folks: I'm not much of an mm person; let me know if I got anything horribly wrong. Many folks use rsync in their nightly backup jobs. In these applications, speed is of minimal concern and should be sacrificed in order to minimize the effect of rsync on the rest of the machine. When rsync is working on a large directory it can quickly fill the page cache with written data,

On 08/11/2017 04:51 PM, Niels de Vos wrote: > On Fri, Aug 11, 2017 at 12:47:47AM -0400, Raghavendra Gowdappa wrote: >> Hi all, >> >> In a conversation between me, Milind and Csaba, Milind pointed out >> fadvise(2) [1] and its potential benefits to Glusterfs' caching >> translators like read-ahead etc. After discussing about it, we agreed >> that our

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

On Fri, Aug 11, 2017 at 12:47:47AM -0400, Raghavendra Gowdappa wrote: > Hi all, > > In a conversation between me, Milind and Csaba, Milind pointed out > fadvise(2) [1] and its potential benefits to Glusterfs' caching > translators like read-ahead etc. After discussing about it, we agreed > that our performance translators can leverage the hints to provide > better

Hi List, I have updated my rsync fadvise patch which stops rsync from ousting all your other data from cache when running large jobs. I have also written an article about the whole issue. http://insights.oetiker.ch/linux/fadvise.html cheers tobi -- Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten http://it.oetiker.ch tobi@oetiker.ch ++41 62 213 9902

https://bugzilla.samba.org/show_bug.cgi?id=7876 Summary: please implement o_direct Product: rsync Version: 3.1.0 Platform: Other OS/Version: Linux Status: NEW Severity: normal Priority: P3 Component: core AssignedTo: wayned at samba.org ReportedBy: costinel at gmail.com QAContact:

Take 2... this version only adds code to discard the cache on Linux and uses the right name for the fadvise call. It''s a bit ugly - I basically just put #ifdef __linux__ around the fadvise calls - but I don''t have the ability to develop something suitable for Solaris... > Attached is a patch to unstable that stops save/restore/dump from > hosing > Dom0 when dealing

--- builder/pxzcat-c.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/builder/pxzcat-c.c b/builder/pxzcat-c.c index 0bbd296..dec9cc2 100644 --- a/builder/pxzcat-c.c +++ b/builder/pxzcat-c.c @@ -214,8 +214,10 @@ pxzcat (value filenamev, value outputfilev, unsigned nr_threads) unix_error (err, (char *) "ftruncate", outputfilev); } +#if defined HAVE_POSIX_FADVISE /*

Use the FADV_DONTNEED fadvise hint after finishing reading an origin fd in the sender. --- sender.c | 6 ++++++ 1 files changed, 6 insertions(+), 0 deletions(-) diff --git a/sender.c b/sender.c index 59dae7d..a934bfe 100644 --- a/sender.c +++ b/sender.c @@ -338,6 +338,12 @@ void send_files(int f_in, int f_out) if (do_progress) end_progress(st.st_size); + if