user/sven/linux.git/include/linux/crush, branch v4.1.6

crush: straw2 bucket type with an efficient 64-bit crush_ln()

2015-04-22T15:33:43Z

This is an improved straw bucket that correctly avoids any data movement between items A and B when neither A nor B's weights are changed. Said differently, if we adjust the weight of item C (including adding it anew or removing it completely), we will only see inputs move to or from C, never between other items in the bucket. Notably, there is not intermediate scaling factor that needs to be calculated. The mapping function is a simple function of the item weights. The below commits were squashed together into this one (mostly to avoid adding and then yanking a ~6000 lines worth of crush_ln_table): - crush: add a straw2 bucket type - crush: add crush_ln to calculate nature log efficently - crush: improve straw2 adjustment slightly - crush: change crush_ln to provide 32 more digits - crush: fix crush_get_bucket_item_weight and bucket destroy for straw2 - crush/mapper: fix divide-by-0 in straw2 (with div64_s64() for draw = ln / w and INT64_MIN -> S64_MIN - need to create a proper compat.h in ceph.git) Reflects ceph.git commits 242293c908e923d474910f2b8203fa3b41eb5a53, 32a1ead92efcd351822d22a5fc37d159c65c1338, 6289912418c4a3597a11778bcf29ed5415117ad9, 35fcb04e2945717cf5cfe150b9fa89cb3d2303a1, 6445d9ee7290938de1e4ee9563912a6ab6d8ee5f, b5921d55d16796e12d66ad2c4add7305f9ce2353. Signed-off-by: Ilya Dryomov

crush: add SET_CHOOSELEAF_VARY_R step

2014-04-05T04:07:28Z

This lets you adjust the vary_r tunable on a per-rule basis. Reflects ceph.git commit f944ccc20aee60a7d8da7e405ec75ad1cd449fac. Signed-off-by: Ilya Dryomov Reviewed-by: Josh Durgin

crush: add chooseleaf_vary_r tunable

2014-04-05T04:07:26Z

The current crush_choose_firstn code will re-use the same 'r' value for the recursive call. That means that if we are hitting a collision or rejection for some reason (say, an OSD that is marked out) and need to retry, we will keep making the same (bad) choice in that recursive selection. Introduce a tunable that fixes that behavior by incorporating the parent 'r' value into the recursive starting point, so that a different path will be taken in subsequent placement attempts. Note that this was done from the get-go for the new crush_choose_indep algorithm. This was exposed by a user who was seeing PGs stuck in active+remapped after reweight-by-utilization because the up set mapped to a single OSD. Reflects ceph.git commit a8e6c9fbf88bad056dd05d3eb790e98a5e43451a. Signed-off-by: Ilya Dryomov Reviewed-by: Josh Durgin

crush: add set_choose_local_[fallback_]tries steps

2013-12-31T18:32:26Z

This allows all of the tunables to be overridden by a specific rule. Reflects ceph.git commits d129e09e57fbc61cfd4f492e3ee77d0750c9d292, 0497db49e5973b50df26251ed0e3f4ac7578e66e. Signed-off-by: Ilya Dryomov Reviewed-by: Sage Weil

crush: CHOOSE_LEAF -> CHOOSELEAF throughout

2013-12-31T18:32:24Z

This aligns the internal identifier names with the user-visible names in the decompiled crush map language. Reflects ceph.git commit caa0e22e15e4226c3671318ba1f61314bf6da2a6. Signed-off-by: Ilya Dryomov Reviewed-by: Sage Weil

crush: add SET_CHOOSE_TRIES rule step

2013-12-31T18:32:23Z

Since we can specify the recursive retries in a rule, we may as well also specify the non-recursive tries too for completeness. Reflects ceph.git commit d1b97462cffccc871914859eaee562f2786abfd1. Signed-off-by: Ilya Dryomov Reviewed-by: Sage Weil

crush: apply chooseleaf_tries to firstn mode too

2013-12-31T18:32:22Z

Parameterize the attempts for the _firstn choose method, and apply the rule-specified tries count to firstn mode as well. Note that we have slightly different behavior here than with indep: If the firstn value is not specified for firstn, we pass through the normal attempt count. This maintains compatibility with legacy behavior. Note that this is usually *not* actually N^2 work, though, because of the descend_once tunable. However, descend_once is unfortunately *not* the same thing as 1 chooseleaf try because it is only checked on a reject but not on a collision. Sigh. In contrast, for indep, if tries is not specified we default to 1 recursive attempt, because that is simply more sane, and we have the option to do so. The descend_once tunable has no effect for indep. Reflects ceph.git commit 64aeded50d80942d66a5ec7b604ff2fcbf5d7b63. Signed-off-by: Ilya Dryomov Reviewed-by: Sage Weil

crush: new SET_CHOOSE_LEAF_TRIES command

2013-12-31T18:32:21Z

Explicitly control the number of sample attempts, and allow the number of tries in the recursive call to be explicitly controlled via the rule. This is important because the amount of time we want to spend looking for a solution may be rule dependent (e.g., higher for the wide indep pool than the rep pools). (We should do the same for the other tunables, by the way!) Reflects ceph.git commit c43c893be872f709c787bc57f46c0e97876ff681. Signed-off-by: Ilya Dryomov Reviewed-by: Sage Weil

crush: use breadth-first search for indep mode

2013-12-31T18:32:16Z

Reflects ceph.git commit 86e978036a4ecbac4c875e7c00f6c5bbe37282d3. Signed-off-by: Ilya Dryomov Reviewed-by: Sage Weil

crush: return CRUSH_ITEM_UNDEF for failed placements with indep

2013-12-31T18:32:15Z

For firstn mode, if we fail to make a valid placement choice, we just continue and return a short result to the caller. For indep mode, however, we need to make the position stable, and return an undefined value on failed placements to avoid shifting later results to the left. Reflects ceph.git commit b1d4dd4eb044875874a1d01c01c7d766db5d0a80. Signed-off-by: Ilya Dryomov Reviewed-by: Sage Weil