Tuesday, February 10, 2015

The proponents of the Berlin Games react as thin-skinned

The proponents of the Berlin Games react as thin-skinned now on Criticism, now displays a warning on the blog Metronaut. There, a series of posters featuring the last Olympic Games was published in 1936 in Berlin a few days ago. The Nazi propaganda pictures were with the current campaign motto "We want the games - Berlin Olympics" provided. These were on the blog alleged statements by Stefan Thies, spokesman for the Olympic campaign cited. Among other things, he was placed in the mouth: "Berlin at that time was a magnet for people all over the world - and gave the longing for Olympics a real place." Metronaut marked the item dutifully as satire. However, the state of Berlin were the posters are a thorn in the side, and it was the operator of the blog admonish. Metronaut published the Abmahnvorgang in a separate blog post. There is also clear that it could not be fast enough to Abmahnern to remove the motifs from the Internet. Metronaut thus received two letters on the afternoon of February 9th. They both sat bloggers 18 clock on the same day as the deadline to remove the posters. In the grounds of the warning states: "They claim contrary in vorbezeichnetem article in the truth that the expectations reflected in your article poster motifs are poster images of the current Olympic campaign [..] Pease, contractual penalty of law is to cease the dissemination of the complete article like. attached to undertake and implement the relevant period until tonight, Feb. 9 18 clock. "

Creative computer mause

Kreative Computer-Maeuse Creative computer mause

Thursday, August 19, 2010

Oracle loses another DTrace creator

Adam Leventhal, another one of the three Sun engineers who developed DTrace, is leaving Oracle. Bryan Cantrill, another member of the team, left Oracle in July. This leaves only one of the original DTrace team – Mike Shapiro – still with Oracle. Shapiro is one of the signatories of the leaked memo which announced the closing of the OpenSolaris project.
Leventhal said, in a blog posting, that at Sun he had found himself "surrounded by superlative engineers" and that he felt lucky to have worked with Cantrill and Shapiro on DTrace. Most recently, Leventhal had been working on Fishworks, Sun's Solaris based storage system technology. Leventhal does not say what he will be doing next, only that he is "off to look for my next remarkable place and time beyond the walls of Oracle". It is possible he could follow in Cantrill's footsteps; within days of leaving, it was announced he had become Vice President of Engineering at Joyent, one of the companies involved in the OpenSolaris derivative Illumos which was launched at the beginning of August

The 2010 Linux Storage and Filesystem Summit, day 2

The second day of the 2010 Linux Storage and Filesystem Summit was held on August 9 in Boston. Those who have not yet read the coverage from day 1 may want to start there. This day's topics were, in general, more detailed and technical and less amenable to summarization here. Nonetheless, your editor will try his best.


The first session of the day was dedicated to the writeback issue. Writeback, of course, is the process of writing modified pages of files back to persistent store. There have been numerous complaints over recent years that writeback performance in Linux has regressed; the curious reader can refer to this article for some details, or this bugzilla entry for many, many details. The discussion was less focused on this specific problem, though; instead, the developers considered the problems with writeback as a whole.

Sorin Faibish started with a discussion of some research that he has done in this area. The challenges for writeback are familiar to those who have been watching the industry; the size of our systems - in terms of both memory and storage - has increased, but speed of those systems has not increased proportionally. As a result, writing back a given percentage of a system's pages takes longer than it once did. It is always easier for the writeback system to fail to keep up with processes which are dirtying pages, leading to poor performance.

His assertion is that the use of watermarks to control writeback is no longer appropriate for contemporary systems. Writeback should not wait until a certain percentage of memory is dirty; it should start sooner, and, crucially, be tied to the rate with which processes are dirtying pages. The system, he says, should work much more aggressively to ensure that the writeback rate matches the dirty rate.

From there, the discussion wandered through a number of specific issues. Linux writeback now works by flushing out pages belonging to a specific file (inode) at a time, with the hope that those pages will be located nearby on the disk. The memory management code will normally ask the filesystem to flush out up to 4MB of data for each inode. One poorly-kept secret of Linux memory management is that filesystems routinely ignore that request - they typically flush far more data than requested if there are that many dirty pages. It's only by generating much larger I/O requests that they can get the best performance.