Date: Wed, 08 Sep 2010 10:19:48 +0300 From: Andriy Gapon <avg@freebsd.org> To: Wiktor Niesiobedzki <bsd@vink.pl>, Pawel Jakub Dawidek <pjd@freebsd.org>, Konstantin Belousov <kib@freebsd.org> Cc: freebsd-fs@freebsd.org Subject: Re: zfs very poor performance compared to ufs due to lack of cache? Message-ID: <4C873914.40404@freebsd.org> In-Reply-To: <4C85E91E.1010602@icyb.net.ua> References: <5DB6E7C798E44D33A05673F4B773405E@multiplay.co.uk> <AANLkTikNhsj5myhQCoPaNytUbpHtox1vg9AZm1N-OcMO@mail.gmail.com> <4C85E91E.1010602@icyb.net.ua>
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on 07/09/2010 10:26 Andriy Gapon said the following:
> Interesting. I briefly looked at the code in mappedread(), zfs_vnops.c, and I
> have a VM question.
> Shouldn't we mark the corresponding page bits as valid after reading data into
> the page?
> I specifically speak of the block that starts with the following line:
> } else if (m != NULL && uio->uio_segflg == UIO_NOCOPY) {
> I am taking mdstart_swap as an example and it does m->valid = VM_PAGE_BITS_ALL.
>
I've chatted with and conclusion seems to be that vm_page_set_validclean() call
should be added at the end of the block.
Perhaps, something like this:
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c
@@ -500,6 +500,7 @@ again:
sched_unpin();
}
VM_OBJECT_LOCK(obj);
+ vm_page_set_validclean(m, off, bytes);
vm_page_wakeup(m);
if (error == 0)
uio->uio_resid -= bytes;
BTW, I think that 'off' variable can be made of 'int' type, as it is an offset
within a page; no need for int64.
--
Andriy Gapon
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