On 7/10/19 4:19 PM, Dave Hansen wrote: > On 7/10/19 12:51 PM, Nitesh Narayan Lal wrote: >> This patch series proposes an efficient mechanism for reporting free memory >> from a guest to its hypervisor. It especially enables guests with no page cache >> (e.g., nvdimm, virtio-pmem) or with small page caches (e.g., ram > disk) to >> rapidly hand back free memory to the hypervisor. >> This approach has a minimal impact on the existing core-mm infrastructure. >> >> Measurement results (measurement details appended to this email): >> *Number of 5GB guests (each touching 4GB memory) that can be launched >> without swap usage on a system with 15GB: > This sounds like a reasonable measurement, but I think you're missing a > sentence or two explaining why this test was used. I will re-work the cover email to better communicate the numbers. > >> unmodified kernel - 2, 3rd with 2.5GB > What does "3rd with 2.5GB" mean? The third gets 2.5GB before failing an > allocation and crashing? It doesn't crash or fail. To complete the execution of the test application which allocates 4GB memory in the 3rd guest 2.5GB swap has been accessed. > >> v11 page hinting - 6, 7th with 26MB >> v1 bubble hinting[1] - 6, 7th with 1.8GB (bubble hinting is another series >> proposed to solve the same problems) > Could you please make an effort to format things so that reviewers can > easily read them? Aligning columns and using common units would be very > helpful, for instance: > > unmodified kernel - 2, 3rd with 2.50 GB > v11 page hinting - 6, 7th with 0.03 GB > v1 bubble hinting[1] - 6, 7th with 1.80 GB > > See how you can scan that easily and compare between the rows? > > I think you did some analysis below. But, that seems misplaced. It's > better to include the conclusion here and the details to back it up > later. As it stands, the cover letter just throws some data at a > reviewer and hopes they can make sense of it. I will improve this. Thanks. > >> *Memhog execution time (For 3 guests each of 6GB on a system with 15GB): >> unmodified kernel - Guest1:21s, Guest2:27s, Guest3:2m37s swap used = 3.7GB >> v11 page hinting - Guest1:23s, Guest2:26s, Guest3:21s swap used = 0 >> v1 bubble hinting - Guest1:23, Guest2:11s, Guest3:26s swap used = 0 > Again, I'm finding myself having to reformat your data just so I can > make sense of it. You also forgot the unit for Guest 1 in row 3. > > unmodified - Guest1:21s, Guest2:27s, Guest3:2m37s swap used = 3.7GB > > v11 hinting - Guest1:23s, Guest2:26s, Guest3:21s swap used = 0 > v1 bubble - Guest1:23s, Guest2:11s, Guest3:26s swap used = 0 > > So, what is this supposed to show? What does it mean? Why do the > numbers vary *so* much? Basically, the idea was to communicate that with hinting swap was not accessed and hence the time of execution is lower. But as you already mentioned next time around I will format this and add the conclusion along with these numbers. I agree with Alexander's comment that there is no point of having the same thing at two place. -- Thanks Nitesh
