On 05/07/2002 12:57 AM, Chris Mason wrote: > On Mon, 2002-05-06 at 17:21, Hans Reiser wrote: > >>>I'd rather not put it back in because it adds yet another corner case to >>>maintain for all time. Most of the fsync/O_SYNC bound applications are >>>just given their own partition anyway, so most users that need data >>>logging need it for every write. >>> >>> >>Does mozilla's mail user agent use fsync? Should I give it its own >>partition? I bet it is fsync bound....;-) >> > > [ I took Wayne off the cc list, he's probably not horribly interested ] > > Perhaps, but I'll also bet the fsync performance hit doesn't affect the > performance of the system as a whole. Remember that data=journal > doesn't make the fsyncs fast, it just makes them faster. > > >>Most persons using small fsyncs are using it because the person who >>wrote their application wrote it wrong. What's more, many of the >>persons who wrote those applications cannot understand that they did it >>wrong even if you tell them (e.g. qmail author reportedly cannot >>understand, sendmail guys now understand but had Kirk McKusick on their >>staff and attending the meeting when I explained it to them so they are >>not very typical....). >> >>In other words, handling stupidity is an important life skill, and we >>all need to excell at it.;-) >> > > A real strength to linux is the application designers can talk directly > to their own personal bottlenecks. Hopefully we reward those that hunt > us down and spend the time convincing us their applications are worth > tuning for. They then proceed to beat the pants off their competition. > > >>Tell me what your thoughts are on the following: >> >>If you ask randomly selected ReiserFS users (not the reiserfs-list, but >>the ones who would never send you an email....) the following >>questions, what percentage will answer which choice? >> >>The filesystem you are using is named: >> >>a) the Performance Optimized SuSE FS >> >>b) NTFS >> >>c) FAT >> >>d) ext2 >> >>e) ReiserFS >> > > I believe the ones that know what a filesystem is will answer ReiserFS, > You might get a lot of ext2 answers, just because that's what a lot of > people think the linux filesystem is. > > >>If you want to change reiserfs to use data journaling you must do which: >> >>a) reinstall the reiserfs package using rpm >> >>b) modify /etc/fs.conf >> >>c) reinstall the operating system from scratch, and select different >>options during the install this time >> >>d) reformat your reiserfs partition using mkreiserfs >> >>e) none of the above >> >>f) all of the above except e) >> > > These people won't be admins of systems big enough for the difference to > matter. data journaling is targeted at people with so much load they > would have to buy more hardware to make up for it. The new option > lowers the price to performance ratio, which is exactly what we want to > do for sendmails, egeneras, lycos, etc. If it takes my laptop 20ms to > deliver a mail message, cutting the time down to 10ms just won't matter. > > >> >>What do you think the chances are that you can convince Hubert that >>every SuSE Enterprise Edition user should be asked at install time if >>they are going to use fsync a lot on each partition, and to use a >>different fstab setting if yes? >> > > Very little, I might tell them to buy the suse email server instead, > since that would have the settings done right. data=journal is just a > small part of mail server tuning. > > >>I know that you are an experienced sysadmin who was good at it. Your >>intuition tells you that most sysadmins are like the ones you were >>willing to hire into your group at the university. They aren't. >> >>Linux needs to be like a telephone. You plug it in, push buttons, and >>talk. It works well, but most folks don't know why. >> >> > > Exactly. I think there are 3 classes of users at play here. > > 1) Those who don't understand and don't have enough load to notice. > 2) Those who don't understand and do have enough load to notice. > 3) Those who do understand and do have enough load to notice. > > #2 will buy support from someone, and they should be able to configure > the thing right. > > #3 will find the docs and do it right themselves. > > >>A moderate number of programs are small fsync bound for the simple >>reason that it is simpler to write them that way. We need to cover >>over their simplistic designs. >> >>So, you have my sympathies Chris, because I believe you that it makes >>the code uglier and it won't be a joy to code and test. I hope you also >>see that it should be done. >> > > Mostly, I feel this kind of tuning is a mistake right now. The patch is > young and there are so many places left to tweak...I'm still at the > stage where much larger improvements are possible, and a better use of > coding time. Plus, it's monday and it's always more fun to debate than > give in on mondays. > > -chris >
Hi, Chris & Hans! Don't think this somekind of destructive discussion would lead to anything useful for now, can you post a diff for 2.4.19-pre7+latest-related-pending +compound-patch-from-ftp? I'll try it and report if that leads to more security and/or less performance on my every day use with NS6 and so on if there is any. Thanks, Manuel
