Messages in this thread | | | Date | Tue, 29 Sep 2009 17:46:35 +0530 | Subject | Re: GFP_NOWAIT and GFP_NOMEMALLOC | From | "Leonidas ." <> |
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On Tue, Sep 29, 2009 at 5:29 PM, Arjan van de Ven <arjan@infradead.org> wrote: > On Tue, 29 Sep 2009 16:55:24 +0530 > "Leonidas ." <leonidas137@gmail.com> wrote: > >> Hi list, >> >> I am new here, I have googled/binged enough before posting this >> message, in case of redundancy please point me to appropriate >> links/resources etc. >> >> I want to kmalloc memory while holding spinlocks in process context, >> here I can't use GFP_KERNEL flag since it can sleep. Using GFP_ATOMIC >> guarantees that allocation will succeed by allocating from emergency >> pools if needed. But I dont think, I need to use emergency pool and I >> want to limit my memory consumption to ZONE_NORMAL without sleeping, >> my module is ready to handle the allocation failure if any. > > GFP_NOWAIT is what you want. > > can you give us a pointer to what your module is about? Maybe there's > better solutions... > > > -- > Arjan van de Ven Intel Open Source Technology Centre > For development, discussion and tips for power savings, > visit http://www.lesswatts.org >
The module is going to be a profiling module and the user module which is under profiling will call the apis which I am exporting. My apis will collect certain data from point it is called and populate internal data strcuctures. My apis can be called from process context as well as interrupt context hence I am using spinlocks as locking mechanism. The amount of memory I am allocating each time my api is called around 100 bytes, and in worst case I might end up allocating tens of thousands of objects of almost same size. I am aware that in such a scenario I should be using some kind of memory pool mechanism and preallocate my buffers to avoid frequent allocations/deallocations.
But frankly, I am not very familiar with Linux kernel apis yet hence have resorted to using a tree data structure for the first cut where I allocate memory as needed depending on the context I am executing in. To optimize a bit, I do not free my memory till some threshold is reached.
Some questions here:
1. GFP_NOWAIT as in kmalloc(size, GFP_KERNEL | GFPNOWAIT)?
or
kmalloc(size, GFP_NOWAIT), I know this one is a dumb one.
2. Any reference for the mempool kind of implementation mentioned above?
3. Any other pointers about design, references etc would be helpful.
-Leo. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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