linux-kernel - Re: [PATCH] fs: aio: Transition from Linked List to Hash Table for Active Request Management in AIO

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Message-ID: <20241022070329.144782-1-pvmohammedanees2003@gmail.com>
Date: Tue, 22 Oct 2024 12:33:27 +0530
From: Mohammed Anees <pvmohammedanees2003@...il.com>
To: willy@...radead.org
Cc: bcrl@...ck.org,
	brauner@...nel.org,
	jack@...e.cz,
	linux-aio@...ck.org,
	linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	pvmohammedanees2003@...il.com,
	viro@...iv.linux.org.uk
Subject: Re: [PATCH] fs: aio: Transition from Linked List to Hash Table for Active Request Management in AIO

Hi Matthew,

> Benchmarks, please.  Look at what operations are done on this list.
> It's not at all obvious to me that what you've done here will improve
> performance of any operation.

This patch aims to improve this operation in io_cancel() syscall,
currently this iterates through all the requests in the Linked list,
checking for a match, which could take a significant time if the 
requests are high and once it finds one it deletes it. Using a hash
table will significant reduce the search time, which is what the comment
suggests as well.

/* TODO: use a hash or array, this sucks. */
	list_for_each_entry(kiocb, &ctx->active_reqs, ki_list) {
		if (kiocb->ki_res.obj == obj) {
			ret = kiocb->ki_cancel(&kiocb->rw);
			list_del_init(&kiocb->ki_list);
			break;
		}
	}

I have tested this patch and believe it doesn’t affect the 
other functions. As for the io_cancel() syscall, please let 
me know exactly how you’d like me to test it so I can benchmark 
it accordingly.

Thanks!!