| Commit message (Collapse) | Author | Age | Files | Lines |
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This is a first step towards the Secure Shared Memory (SSM)
infrastructure for Ouroboros, which will allow proper resource
separation for non-privileged processes.
This replaces the rdrbuff (random-deletion ring buffer) PoC allocator
with a sharded slab allocator for the packet buffer pool to avoid the
head-of-line blocking behaviour of the rdrb and reduce lock contention
in multi-process scenarios. Each size class contains multiple
independent shards, allowing parallel allocations without blocking.
- Configurable shard count per size class (default: 4, set via
SSM_POOL_SHARDS in CMake). The configured number of blocks are
spread over the number of shards. As an example:
SSM_POOL_512_BLOCKS = 768 blocks total
These 768 blocks are shared among 4 shards
(not 768 × 4 = 3072 blocks)
- Lazy block distribution: all blocks initially reside in shard 0
and naturally migrate to process-local shards upon first
allocation and subsequent free operations
- Fallback with work stealing: processes attempt allocation from
their local shard (pid % SSM_POOL_SHARDS) first, then steal
from other shards if local is exhausted, eliminating
fragmentation while maintaining low contention
- Round-robin condvar signaling: blocking allocations cycle
through all shard condition variables to ensure fairness
- Blocks freed to allocator's shard: uses allocator_pid to
determine target shard, enabling natural load balancing as
process allocation patterns stabilize over time
Maintains existing robust mutex semantics including EOWNERDEAD
handling for dead process recovery. Internal structures exposed in
ssm.h for testing purposes. Adds some tests (pool_test,
pool_sharding_test.c. etc) verifying lazy distribution, migration,
fallback stealing, and multiprocess behavior.
Updates the ring buffer (rbuff) to use relaxed/acquire/release
ordering on atomic indices. The ring buffer requires the (robust)
mutex to ensure cross-structure synchronization between pool buffer
writes and ring buffer index publication.
Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
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Slow but steady.
Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
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2022 was a rather slow year...
Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
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Growing pains.
Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
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The ugent email addresses are shut down, updated to Ouroboros mail
addresses.
Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
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Happy New Year, Ouroboros!
Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
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The rbuff_destroy function asserts that we do not try to destroy an
rbuff that still contains packets. The test now empties the rbuff
before destroying it.
Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
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Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
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This adds some tests for the shm_rbuff after some reports that the
queue length would be erroneously reported as 0 when the rbuff was
full. The test passes for the reported case.
Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
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