similar to: nbdkit background threads

On Mon, Feb 10, 2020 at 01:52:25PM -0600, Eric Blake wrote: > On 2/10/20 1:39 PM, Richard W.M. Jones wrote: > >https://github.com/libguestfs/nbdkit/blob/ecef5b16359fb5af7e7abf4fd2fb3ad5438b16be/TODO#L76 > > > >Already existing filters (readahead, cache) could be improved if > >filters could open a background work thread or threads which connect > >independently to

On 2/10/20 1:39 PM, Richard W.M. Jones wrote: > https://github.com/libguestfs/nbdkit/blob/ecef5b16359fb5af7e7abf4fd2fb3ad5438b16be/TODO#L76 > > Already existing filters (readahead, cache) could be improved if > filters could open a background work thread or threads which connect > independently to the plugin. A proposed new filter (scan) cannot > really be written at all

I'm impressed that I was able to whip this out in just one day of hacking. Below, I'll include a diff between the plugin and the filter as of patch 1, if it aids review. Eric Blake (3): filters: Add ext2 filter ext2: Deprecate ext2 plugin ext2: Add mode for letting client exportname choose file from image TODO | 5 - configure.ac

Applies on top of my pending series for the exportname filter, addressing one of the todo's in that cover letter. Eric Blake (2): filters: Add .export_description wrappers ext2: Supply .list_exports and .default_export filters/ext2/nbdkit-ext2-filter.pod | 3 +- tests/Makefile.am | 16 +++- filters/ext2/ext2.c | 125 +++++++++++++++++++---------

Based on Rich's review of my v1 that touched only cache.c, I have now tried to bring all three filters with alignment rounding in line with one another. There is definitely room for future improvements once we teach nbdkit to let filters and plugins advertise block sizes, but I'm hoping to get NBD_CMD_CACHE implemented first. Eric Blake (2): blocksize: Process requests in linear order

On Thu, Oct 03, 2019 at 09:54:37PM -0500, Eric Blake wrote: > Although it is unusual for a plugin to shrink size on reopen, it is > not impossible. Failure to check our bounds could result in violating > assumptions in the plugin that all requests are in-bounds. Note that > if the plugin gains a larger size, we merely never access the new tail > of the file (when the NBD protocol

Here's what I'm currently playing with; I'm not ready to commit anything until I rebase my FUA work on top of this, as I only want to break filter ABI once between releases. Eric Blake (2): backend: Rework internal/filter error return semantics filters: Add log filter TODO | 2 - docs/nbdkit-filter.pod | 84 +++++++-- docs/nbdkit.pod

I do have a question about whether patch 2 is right, or whether I've exposed a bigger problem in the truncate (and possibly other) filter, but the rest seem fairly straightforward. Eric Blake (4): server: Check for pthread lock failures truncate: Factor out reading real_size under mutex plugins: Check for mutex failures filters: Check for mutex failures filters/cache/cache.c

It's confusing to use the same terminology for a single backend as for the linked list of backends. In particular it's often not clear if we're calling the next backend or the whole chain of backends. --- server/internal.h | 14 ++++++++++-- server/connections.c | 20 ++++++++--------- server/locks.c | 2 +- server/main.c

Includes a rework of the previously posted patch for --run improvements (mostly with improved comments and commit message; I decided that waiting for the captive nbdkit to exit was overkill), and four new patches. The tests are intentionally separate, to allow rearranging the order of the series to see the failures being fixed. Eric Blake (6): server: Propagate unexpected nbdkit failure with

After more than a month since v2 [1], I've finally got my FUA support series polished. This is all of my outstanding patches, even though some of them were originally posted in separate threads from the original FUA post [2], [3] [1] https://www.redhat.com/archives/libguestfs/2018-January/msg00113.html [2] https://www.redhat.com/archives/libguestfs/2018-January/msg00219.html [3]

Since v1: add the blocksize filter, add testsuite coverage of the log filter, several fixes to the log filter based on what adding tests revealed I'm still working on FUA flag support patches on top of this; the patches should all be committed in the same release, as we want to minimize the number of releases that cause a filter ABI/API bump Eric Blake (3): backend: Rework internal/filter

While working on adding assertions to pthread_mutex_lock calls, I noticed that the truncate filter's use of mutex didn't really protect us, and isn't really necessary. Cleaning that up also spotted a couple of other potential cleanups. Eric Blake (4): filters: Drop useless .open callbacks truncate: Fix corruption when plugin changes per-connection size truncate: Test for safe

Rebased filters patch. Requires current git master + the locks / thread model fix (https://www.redhat.com/archives/libguestfs/2018-January/msg00128.html) So a few changes here since last time: The "introduce filters" and "implement filters" patches are squashed together. I introduced a concept of .prepare and .finalize. These run before and after the data serving phase

I still don't have .prepare/.finalize working cleanly across reopen, but did find a nasty bug where a botched assertion means we failed to notice reads beyond EOF in both the xz and retry filter. Refactoring backend.c will make .finalize work easier. Eric Blake (5): xz: Avoid reading beyond EOF retry: Check size before transactions tests: Test retry when get_size values change

I think this is my last round of patches for issues I identified with the retry filter. With this in place, it should be safe to interject another filter in between retry and the plugin. Eric Blake (5): retry: Don't call into closed plugin tests: Refactor test-retry-reopen-fail.sh tests: Enhance retry test to cover failed reopen server: Move prepare/finalize/close recursion to

Two hopefully useful additions to the fua filter. The second one is kind of like cache=unsafe in qemu, in that it exchanges correctness for speed. Useful for data which is easily recreated in the event of a crash or for people who like living on the edge and have good backups. Rich.

This patch series enhances the cache filter in a few ways, primarily adding a "cache-on-read" feature (similar to qemu's copyonread); and adding the ability to limit the cache size and the antecedent of that which is having a method to reclaim cache blocks. As the cache is stored as a sparse temporary file, reclaiming cache blocks simply means punching holes in the temporary file.

This tentative commit implements extents/can_extents, roughly as discussed in the previous thread here: https://www.redhat.com/archives/libguestfs/2019-March/msg00017.html I can't say that I'm a big fan of having the plugin allocate an extents array. There are no other plugin callbacks currently where we require the plugin to allocate complex data structures (or indeed do any allocation

- Use more friendly output with GiB and MiB/s - Measure time per operation, providing finer grain stats - Add total stats for understanding system throughput - Add missing stats for flush I hope that these changes will help to understand and improve virt-v2v performance. Changes since v1: - Keep bytes values - Increase precision to 0.001 GiB and 0.001 MiB/s - Add total stats - Show time before