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Linux 2.4.7pre5aa1 Released

Jul 11, 2001, 01:30 (1 Talkback[s])
Date:   Wed, 11 Jul 2001 02:45:06 +0200
From: Andrea Arcangeli <andrea@suse.de>
Subject: 2.4.7pre5aa1

Diff between 2.4.7pre3aa1 and 2.4.7pre5aa1:

Only in 2.4.7pre3aa1: 00_async-io-unlock-race-1
Only in 2.4.7pre3aa1: 00_cpus_allowed-1

        Merged in mainline.

Only in 2.4.7pre3aa1: 00_bh-async-1
Only in 2.4.7pre5aa1: 00_bh-async-2

        Rediffed against pre5 due trivial rejects.

Only in 2.4.7pre5aa1: 00_create_bounces-sleeps-1

        Kill KM_BOUNCE_WRITE and use kmap instead of kmap_atomic+cli in the
        write-bounce case since create_bounces is allowed to sleep.

Only in 2.4.7pre5aa1: 00_drop___unlock_buffer-1

        Rename __unlock_buffer to unlock_buffer. I did it before knowing Linus
        did it too sorry.

Only in 2.4.7pre5aa1: 00_drop_async-io-get_bh-1

        Drop the get_bh/atomic_inc around the async I/O, for any bh that uses
        set_buffer_async_io the page will be locked for the whole duration of
        the I/O (that's why you use set_buffer_async_io in first place) so the
        bh doesn't need the additional b_count protection during the I/O and we
        this way we can save some cycle.

Only in 2.4.7pre5aa1: 00_drop_end_buffer_write-1

        Drop end_buffer_write and replace with the sync_io callback to avoid
        wasting icache. Here too I should have waited for pre6 but I just
        did it.

Only in 2.4.7pre5aa1: 00_drop_write_unlocked-get_bh-1

        Micro-optimize a bit in write_unlocked_buffers: the get_bh is needed
        only if the buffer was dirty and we are going to do the I/O on it (all
        the rest is protected by the lru_list_lock).

Only in 2.4.7pre5aa1: 00_kiobuf-backout-get_bh-1

        Remove the get_bh/put_bh around the kiobuf driven I/O, the notifion of
        the refernece count and of I/O in flight belongs to the kiobuf not to
        the bh, the bh are just an array of ram in the kiobuf, and this way we
        save some cycle.

Only in 2.4.7pre3aa1: 00_ksoftirqd-7_ppc-2
Only in 2.4.7pre3aa1: 00_ksoftirqd-8

        ksoftirqd is in mainline. All ports needs to synchronize now.
        Alpha and x86 are uptodate in pre5. I uptodate uml in my tree
        to get it right too.

        For port maintainers: in short you need to do the:

                if (pending_softirq(cpu))

        check only when returning from irqs that can post softirq events (for
        example IPI never post softirq events currently, theoretically you
        could with the smp_call but nobody uses it that way at the moment). For
        example x86 and alpha do the check in C in the last few lines of C of
        the irq handler.

        You _don't_ need to check for pending softirq when returning
        from kernel to userspace any longer, that case is now handled with
        ksoftirqd, this gives higher performance in the ret-to-userspace and
        reschedule fast paths (that is the change made by Linus).

        As usual ksoftirqd keeps handling the overflow case.

Only in 2.4.7pre5aa1: 00_linus-brelse-fix-1

        This is a patch from Linus to fix a race condition he spotted in brelse
        that could trigger on architectures where the atomic_t changes don't
        imply SMP memory barriers at the CPU level.

Only in 2.4.7pre3aa1: 00_meminfo-wraparound-1
Only in 2.4.7pre5aa1: 00_meminfo-wraparound-2

        Rediffed to fixup trivial rejects.

Only in 2.4.7pre3aa1: 00_msync-fb0-1

        Merged in mainline.

Only in 2.4.7pre5aa1: 00_o_direct-10
Only in 2.4.7pre3aa1: 00_o_direct-9

        Fixed O_SYNC|O_DIRECT, when O_SYNC was used in combination with
        O_DIRECT it was returning a short write even if all the I/O was
        reaching the disk succesfully and the f_pos was updated correctly, (in
        my regression testing of O_SYNC|O_DIRECT I obviously forgotten to check
        for short writes, I was only checking for errors and it was working
        like a charm). Thanks to Peter for spotting and reporting this.

        Fixed also another bug that could forget to wait for I/O completion
        of async I/O for O_SYNC/fsync/fdatasync.

Only in 2.4.7pre3aa1: 51_uml-ac-to-aa-1.bz2
Only in 2.4.7pre5aa1: 51_uml-ac-to-aa-2.bz2

        Updated to pre5 ksoftirqd logic.

Available at:


A fixed O_DIRECT patch against vanilla 2.4.7pre5 is here: