Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 56c10372 authored by Angelo G. Del Regno -- EternityProject Team Manager's avatar Angelo G. Del Regno -- EternityProject Team Manager Committed by Andrea
Browse files

fs: aio: Optimization for SSD-only machines 

If the system is running on NAND-based storage, without
mechanical drives, we don't need to manage the plug/unplug
of the actual block because we don't have to count the
time for the head to reach that disk physical location.
Solid state storage have no head to move and no location
to "physically reach", as the block is being retrieved
in the exact moment we request it.

The do_io_submit function expects the storage device to
be ready to deliver the block (aka - next block of the
queue to process), therefore it's safe to remove useless
waits on systems using only that type of storage.

This patch adds a configuration option to enable the
SSD-only optimization for the Linux Asynchronous IO
framework.
Enabling it on systems with rotational storage (or mixed)
WILL hit storage performance A LOT.
parent 70be84de

fs/aio.c

+6 −0
Original line number Diff line number Diff line
@@ -1600,7 +1600,9 @@ long do_io_submit(aio_context_t ctx_id, long nr, 
	struct kioctx *ctx;

	long ret = 0;

	int i = 0;

#ifndef CONFIG_AIO_SSD_ONLY

	struct blk_plug plug;

#endif



	if (unlikely(nr < 0))

		return -EINVAL;
@@ -1617,7 +1619,9 @@ long do_io_submit(aio_context_t ctx_id, long nr, 
		return -EINVAL;

	}



#ifndef CONFIG_AIO_SSD_ONLY

	blk_start_plug(&plug);

#endif



	/*

	 * AKPM: should this return a partial result if some of the IOs were
@@ -1641,7 +1645,9 @@ long do_io_submit(aio_context_t ctx_id, long nr, 
		if (ret)

			break;

	}

#ifndef CONFIG_AIO_SSD_ONLY

	blk_finish_plug(&plug);

#endif



	percpu_ref_put(&ctx->users);

	return i ? i : ret;

init/Kconfig

+15 −0
Original line number Diff line number Diff line
@@ -1724,6 +1724,21 @@ config AIO 
	  by some high performance threaded applications. Disabling

	  this option saves about 7k.



config AIO_SSD_ONLY

	bool "Tune AIO performance for SSDs" if EXPERT

	default n

	depends on AIO

	help

	  Solid state storage have no head to move and no location

	  to "physically reach", as the block is being retrieved

	  in the exact moment we request it.

	  Optimize Asynchronous IO for those conditions.



	  Enabling this option on systems with rotational drives

	  WILL be resulting in bad storage performance.



	  If you've got ONLY SSDs, say Y. If unsure, say N.



config ADVISE_SYSCALLS

	bool "Enable madvise/fadvise syscalls" if EXPERT

	default y