Date: Mon, 12 May 2003 15:48:04 -0400 (EDT) From: John Baldwin <jhb@FreeBSD.org> To: Jeff Roberson <jroberson@chesapeake.net> Cc: arch@freebsd.org Subject: Re: [Bikeshed] sigacts locking Message-ID: <XFMail.20030512154804.jhb@FreeBSD.org> In-Reply-To: <20030509201646.Q99131-100000@mail.chesapeake.net>
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On 10-May-2003 Jeff Roberson wrote: > On Fri, 9 May 2003, John Baldwin wrote: > >> As part of the locking for the proc structure, I needed to lock >> the procsig and sigacts stuctures so that kill(), killpg(), >> sigaction() and a few other system calls can be pulled out from >> under Giant. After talking with Peter some, I decided to >> pull the sigacts structure out of the u-area and merge it with >> the procsig structure under the sigacts name. I then added a >> mutex to each sigacts and added locking where appropriate. With >> this change, the aforementioned system calls are now MP safe >> along with sendsig(), *signal(), cursig(), etc. The patch for >> all this is at http://www.FreeBSD.org/~jhb/patches/sigacts.patch >> I would appreciate comments, review, etc. that people may have. >> If all goes well I hope to get this into 5.1. Thanks. >> > > I'm all for this, but I have a few concerns. Right now the UAREA is > mostly taken up by sigacts. Without it the page is quite empty. This > means that we'll be allocating more storage elsewhere while leaving this > for nothing. > > Have you given any thought to removing the other bits from uarea, or > allocating uarea using a zone instead of a whole page? Alternatively, you > could disable paging for the uarea and leave sigacts in it. Leaving sigacts in the u-area is quite ugly because for rfork() RFTHREAD processes we don't use the sigacts in the u-area, we use a malloc'd one instead. Accomplishing that is quite ugly. > I just hate to s ee the wasted space. I don't have any future plans for the u-area specifically. Any of your suggestions (using a zone, axeing it completely, etc.) sound fine to me as to how to avoid wasting space. -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/
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