So, what is it`seqlock` synchronization primitive and how does it work? Let's try to answer on these questions in this paragraph. Actually `sequential locks` were introduced in the Linux kernel 2.6.x. Main point of this synchronization primitive is to provide fast and lock-free access to shared resources. Since the heart of `sequential lock` synchronization primitive is [spinlock](https://0xax.gitbooks.io/linux-insides/content/SyncPrim/sync-1.html) synchronization primitive, `sequential locks` work in situations where the protected resources are small and simple. Additionally write access must be rare and also should be fast.
So, what is a`seqlock` synchronization primitive and how does it work? Let's try to answer on these questions in this paragraph. Actually `sequential locks` were introduced in the Linux kernel 2.6.x. Main point of this synchronization primitive is to provide fast and lock-free access to shared resources. Since the heart of `sequential lock` synchronization primitive is [spinlock](https://0xax.gitbooks.io/linux-insides/content/SyncPrim/sync-1.html) synchronization primitive, `sequential locks` work in situations where the protected resources are small and simple. Additionally write access must be rare and also should be fast.
Work of this synchronization primitive is based on the sequence of events counter. Actually a `sequential lock` allows free access to a resource for readers, but each reader must check existence of conflicts with a writer. This synchronization primitive introduces a special counter. The main algorithm of work of `sequential locks` is simple: Each writer which acquired a sequential lock increments this counter and additionally acquires a [spinlock](https://0xax.gitbooks.io/linux-insides/content/SyncPrim/sync-1.html). When this writer finishes, it will release the acquired spinlock to give access to other writers and increment the counter of a sequential lock again.
Tim
8 years ago