Autolocker: synchronization inference for atomic sections

The movement to multi-core processors increases the need for simpler, more robust parallel programming models. Atomic sections have been widely recognized for their ease of use. They are simpler and safer to use than manual locking and they increase modularity. But existing proposals have several practical problems, including high overhead and poor interaction with I/O. We present pessimistic atomic sections, a fresh approach that retains many of the advantages of optimistic atomic sections as seen in “transactional memory ” without sacrificing performance or compatibility. Pessimistic atomic sections employ the locking mechanisms familiar to programmers while relieving them of most burdens of lock-based programming, including deadlocks. Significantly, pessimistic atomic sections separate correctness from performance: they allow programmers to extract more parallelism via finergrained locking without fear of introducing bugs. We believe this property is crucial for exploiting multi-core processor designs. We describe a tool, Autolocker, that automatically converts pessimistic atomic sections into standard lock-based code. Autolocker relies extensively on program analysis to determine a correct locking policy free of deadlocks and race conditions. We evaluate the expressiveness of Autolocker by modifying a 50,000 line highperformance web server to use atomic sections while retaining the original locking policy. We analyze Autolocker’s performance using microbenchmarks, where Autolocker outperforms software transactional memory by more than a factor of 3

Lifting abstract interpreters to quantified logical domains

We describe a general technique for building abstract interpreters over powerful universally quantified abstract domains that leverage existing quantifier-free domains. Our quantified abstract domain can represent universally quantified facts like ∀i(0 ≤ i < n ⇒ a[i] = 0). The principal challenge in this effort is that, while most domains supply over-approximations of operations like join, meet, and variable elimination, working with the guards of quantified facts requires under-approximation. We present an automatic technique to convert the standard over-approximation operations provided with all domains into sound under-approximations. We establish the correctness of our abstract interpreters by identifying interpreter and another that defines its precision, or completeness. Our experiments on a variety of programs using arrays and pointers (including several sorting algorithms) demonstrate the feasibility of the approach on challenging examples

Efficacy of Norflurazon for Nutsedge Control in Parker Valley Alfalfa

Summer weeds such as nutsedge are of economic concern to alfalfa growers in western Arizona. A two year replicated evaluation of the effectiveness of granular norflurazon herbicide for purple nutsedge control was conducted on an established alfalfa field in La Paz County. Zorial Rapid 80 WP and Evital 5G herbicides were tested for their effectiveness at controlling purple nutsedge when applied following hay harvest but prior to irrigation in early spring and late summer. Zorial 80 WP was applied at 2.0 lb a. i. /acre. Evital 5G was applied in spring 1996 at application rates of 1.0, 1.5, 2.0, and 3.0 lb a. i. /acre. Split applications were made the following summer to four plots for a total of 2.0, 3.0, and 4.0 lb a. i. /acre/year. In 1996, purple nutsedge control resulting from a single application of Evital 5G at 2.0 lb a. i. /acre was 41, 82, and 35% at 35, 63, and 99 DAT, respectively. However, Zorial 80 WP applied at 2.0 lb a. i. /acre provided poor purple nutsedge control due to poor soil incorporation since the liquid was unable to penetrate the dense nutsedge foliage. The treatments were reapplied in spring and summer of 1997

Integrated Morningglory Control Strategies: Transgenic Cotton and Precision Cultivation

A field demonstration was conducted in Mohave Valley to compare cotton morningglory control programs that combined the use of over the top herbicides Roundup Ultra on Roundup Ready cotton (Deltapine 436 RR) or Staple on non-transgenic cotton (SureGrow 125) with and without precision cultivation

Layby Mexican Sprangletop Control with Select (Clethodim) and Antagonism Resulting from Staple (Pyrithiobac Sodium) and Select Tank Mixed

Late emerging summer annual grassy weeds such as Mexican sprangletop can stain cotton lint resulting in price discounts for color at harvest. Cyanizine (Bladex) is commonly applied layby for grassy weed, morningglory, and pigweed control, however use of this herbicide will be phased out by 2002 with rate reductions beginning in 1998. Clethodim (Select) herbicide was evaluated as an alternative to cyanizine for layby grassy weed control, plus the antagonistic effect of tank mixing Select with Staple herbicide was examined in Parker Valley, AZ during the 1997 cotton growing season